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You Can Do Something About the Weather

by Brant Oswald
photos by Brant Oswald
We all know that "predictably good weather" is an oxymoron. Here are several tips — offered for spring creek and tailwater anglers but applicable anywhere — to help you deal with the inevitable and turn the elements to your favor.

Fishing in Bad WeatherANGLING TACTICS are determined by any number of factors, but weather is always one of the most important. When I think of the influences of weather conditions on a fishing situation, I am reminded of a customer who, a few seasons ago, walked into the Livingston, Montana fly shop where I worked. It was one of those days that would frustrate any angler or guide — a beautiful sunny June day in the 70s, but a front was pushing in, and the wind that makes Livingston famous was out in full force. This customer had tried to make the best of the situation on one of the local spring creeks, but the upstream wind had kicked the normally smooth flows into whitecaps, the hatch (what little there was) had been ripped off the water immediately, and casting was almost impossible.

Clearly beaten by the conditions, he came trudging into the shop for advice, hoping we could suggest something that would turn the day around. We just tried to console him, assuring him there was no secret fly pattern or magic technique that would improve the situation. After half an hour of pacing, he finally asked the question: “If you were in my shoes, what would you do on a day like today?” He had asked for it, so one of my co-workers gave him the brutally honest answer: “I’d go home and mow my lawn and fish when the wind isn’t blowing so hard.”

The point is that anglers don’t get to choose the weather for their fishing expeditions. Even those of us who are lucky enough to live close to great trout fishing have jobs, and we can’t abandon the rest of our lives just because fishing conditions are optimal. We schedule a fishing trip for a day off or for a vacation, often weeks or months in advance, and we try to pick an ideal combination of weather, water conditions, and hatches, but it doesn’t always work out as planned. Knowing how to adapt fishing tactics to varying weather conditions is one key to consistent success. In this first part of the article, I will outline some of the generalizations that can be made about hatches and fish behavior with varying seasonal weather patterns. In parts II & III, I’ll discuss dealing with the wind and weather patterns that are typical for areas like Montana’s Paradise Valley.

The first thing I should note is that a number of the lessons about fishing in various weather conditions I have learned by reading the fly fishing literature and confirmed through personal experience. It is unfortunate, but I think sporting writers are particularly guilty in failing to acknowledge the contributions made by others. In the material that follows, I have tried to credit the authors who have instructed me, and though in some cases the books might be out of print, I would encourage a careful reading if possible.

Seasonal Hatch Patterns

Selective Troutw by Doug Swisher and Carl Richards was my bible when I was learning to fish Silver Creek as a teenager, and one of the ideas introduced there is that hatches (mayfly hatches in particular) tend to occur at “the most pleasant time of day for the season.” In spring and fall, most hatches occur in the afternoons, when the air has warmed to its highest point. In mid-summer, most hatch activity occurs in the morning and again in the evening, not during the heat of the day. Recognizing this pattern will allow the angler to anticipate hatch activity over the course of the fishing season.

Just as hatch activity shifts to the cooler times of day during the warmest part of the year, the bugs themselves tend to become smaller and lighter in color as the season progresses.

According to Fred Arbona, Jr., in The Mayflies, the Angler, and the Troutw, this seasonal trend is explained by a mayfly’s need for moisture preservation during its adult life cycle, particularly for keeping the insect’s exoskeleton flexible enough to allow it to molt from dun into spinner. Moderate temperatures and higher humidity are ideal conditions, and mayflies (as well as other aquatic insects) have adapted to hatch at times when their survival rate is highest. It seems to me that these same conditions are also critical even earlier in the life cycle, by allowing the wings of a newly hatched mayfly dun to dry properly. Cooler, humid air allows the wings to dry slowly enough that they can be fully expanded before they harden. On the other hand, for the best chance for survival, the wings should dry quickly enough that the insect can fly off to the cover of streamside vegetation before a bird or trout can pick it off the surface of the water.

Water Temperatures and the Sequence of Hatches

Swisher and Richards’ “pleasant time of day” rule is not precise because it relies on an imperfect correlation between air temperatures and the environmental factors that actually trigger hatches — water temperature and light levels. Arbona points out that water temperature is the chief influence on the maturation rate of nymphs and is therefore the biggest determinant of the seasonal sequence of hatches. This is useful information for the angler because it means that aberrant seasonal weather patterns may have an important effect on the overall timing of hatches. Unusually cold weather or a late spring may delay the onset of hatches, while early warm weather and lower flows in a light snowpack year may allow the nymphs to mature more quickly than normal, allowing hatches to start earlier than expected.

For example, when we have an unseasonably warm April and May in Montana, damsels start to hatch in good numbers on many of the local lakes and ponds by the end of May. This is at least two weeks earlier than we would predict this hatch in a “normal” year. As we will discuss in part II of this article, there is a second set of conditions that trigger a hatch on a given day, but once water temperatures allow the nymphs to reach maturity, they are ready to hatch any time those conditions are met. When planning a trip to meet a certain hatch, it is a good idea to check on water levels and watch weather patterns to see whether to anticipate a shift in the timing of the hatch.

Physical Adaptations to Seasonal Weather

The need for aquatic insects to preserve body moisture has also resulted in physical adaptations to seasonal weather patterns: size and color. Just as hatch activity shifts to the cooler times of day during the warmest part of the year, the bugs themselves tend to become smaller and lighter in color as the season progresses. These adaptations result in less heat absorption in the warm summer months. On spring creeks and tailwaters, we see the shift from the big bugs of early season like Green and Brown Drakes to smaller Pale Morning Duns to even smaller Western Sulfurs and Tricos.

Although many anglers are familiar with the size and color of specific hatches, these seasonal trends can still provide useful fishing information. Mayflies that produce multiple broods during the season will be smaller with each successive brood. Callibaetis mayflies, common on stillwaters and the slower sections of spring creeks and tailwaters, may be as large as a #14 when the first brood hatches in May and June, but a #18 imitation may be just right for the late broods of September. Pale Morning Duns also show a marked shift down in size as the season progresses. (For an excellent recap of Swisher and Richards’ and Arbona’s writings on these seasonal patterns, pick up a copy of Neale Streeks’ Small Fly Adventures in the Westw.)

Becoming familiar with the effect of seasonal weather patterns on hatches may provide some useful information in a given situation, but they are especially important as the background against which to interpret the effect local weather will have during a given day. Next we’ll look at the effects of daily weather patterns.

Familiarity with seasonal correlations between weather and hatches is important, but variations in daily weather patterns are likely to have a more profound influence on angling tactics.

Sunshine vs. Overcast

As a fly shop employee I was always amused by the effect of weather on guides and clients when they met at the shop prior to a trip. On a glorious sunny morning — whether April or June or September — inexperienced clients would be cheerful and talkative as a Montana meadowlark on a prairie fencepost, while their guide would be scowling and muttering to himself as he picked out flies for the day. However, given a morning of heavy overcast and a little drizzle, the clients would ask lots of nervous questions about cancellation fees and raingear, and the guide would be happy as a clam.

Fishing RainbowThis behavior reflects one of the most basic generalizations about weather and spring creek fishing: clouds are an angler’s best friend. Both trout and aquatic insects tend to be more active in low light, and cloudy conditions spread these light conditions over a longer part of the day. The fish are afforded better protection from aerial predators in low light, making them feed more confidently in the clear waters of a spring creek or tailwater. In addition, the eyes of trout are capable of relatively rapid adjustment to changes in light intensity, so they have an advantage over their prey in low light. (For a very informative account of the senses of gamefish, see Through the Fish’s Eye1 by Mark Sosin & John Clark.)

The timing and density of hatches also favors the angler on overcast days. On warm, bright days, hatch activity usually starts earlier in the day but will be shorter in duration, often producing brief but very intense activity. Conversely, on cloudy days, hatches show a later onset, but will produce steady numbers of bugs for a longer period of time. This information is key for an angler planning the day’s tactics based on weather conditions. On a practical level, longer hatches give the angler a better opportunity to make some mistakes and still have a chance to catch a good number of fish. During very intense hatches, the angler sometimes struggles to get his fly noticed among a raft of naturals. The time taken to change flies or untangle a leader may also burn up a large portion of the trout’s feeding activity. The wings of mayfly duns dry more slowly in the cooler air temperatures and higher humidity of an overcast day. The result is an emerging insect that stays on the water longer, making them more vulnerable to the fish — this often allows the angler to switch to more visible dun patterns, rather than relying on emergers through most of the hatch.

The one advantage to bright conditions is that it makes spotting fish below the surface much easier. Of course, in many cases, hatches will be heavy enough on cloudy days that spotting fish will be no more difficult than looking for rise forms.

As an angler or guide, bright morning sun on a spring creek doesn’t scare me. I make use of the good high-angled spotting light on these days to look for nice fish suspended over submerged weed beds. Sight fishing with a midge larva or small mayfly nymph can be deadly in these conditions.

Although fully mature aquatic insects are capable of delaying their emergence for optimal hatch conditions (see Fred Arbona’s The Mayflies, the Angler, and the Trout1), anglers should recognize that mid-summer insects are adapted somewhat to hatching in sunlight, so you are likely to see hatches and feeding fish, even on bright days. If you fish a western spring creek in early July, you will see some Pale Morning Dun mayflies in almost any weather, but the hatch (and fishing) are likely to be even better if you luck into a cloudy day.

Rain and Snow

Most experienced anglers can think back on the best fishing days in memory and find that a good number of them came on days when it was raining or snowing. Precipitation can have a positive effect both on hatch activity and the fish’s willingness to feed. A number of reasons can be given for this. One obvious (but often ignored) reason is that rain or snow comes on days with overcast skies. The mixing action of rain hitting the water’s surface also oxygenates the water, which may raise the activity level of the fish. Rain can also moderate extreme water temperatures, warming cold flows early and late in the season, while an afternoon thundershower can cool warm flows in mid-summer.

My experience is that the best hatch activity and fishing is often not during the precipitation itself, but immediately after it (or in between showers or snow flurries). The high humidity associated with precipitation is also conducive to hatch activity and fishing success for the reasons noted above.

Fishing in Bad WeatherBarometer

Like most anglers, I am convinced that barometric pressure affects fishing, but I don’t think any angler can profess to explain all of its effects. One reason for this is that barometric pressure has a complicated interrelationship with other weather factors we have discussed so far: air temperatures, water temperatures, light intensity, etc. I would agree, for the most part, with Gary Borger’s characterization inPresentation1, that a rapidly changing barometer is usually a problem, and a steady or slow change in barometric pressure will allow for good fishing. (See also the “Sunshine and Shadow” chapter ofTrout1.)

The weather conditions I dread — as a spring creek angler or guide — are days of unsettled, “squirrelly” weather. On days when small fronts are zipping all over the weather map, most guides would prefer to stay home and hide under the covers. On these days, gusty winds change direction constantly, scudding clouds preclude either good spotting light or steady overcast, and a changing barometer seems to keep both bugs and fish at minimal levels of activity.

Gearing Up for Weather

Being able to make some basic predictions about hatches and fish activity because of weather conditions can be a key part of planning one’s tactics for the day. It is equally important to be prepared to fish (comfortably) in any possible weather conditions. Here are a few suggestions on necessary gear for a day on a spring creek or tailwater.

Polarized sunglasses are an absolute must for any fishing, but they are especially critical for the spotting required on spring creeks and tailwaters. Stash a spare pair in your vest or fishing bag (even if they are inexpensive backups) in case you lose or break a pair. For sun protection, be sure to use waterproof sunblock (don’t get so excited to start fishing that you don’t take time to put it on until you are burned) and wear a brimmed hat. Nothing can ruin a fishing vacation faster than a bad sunburn on the first day of the trip.

Fingerless gloves are very popular, but I have always found them a sure way to get the tips of one’s fingers cold. I prefer to wear a full fingered glove that gives me enough dexterity to handle line.

If you fish in higher altitude locations, you know that rapid temperature changes are a common occurrence, so even in the warmest part of the summer carry a fleece jacket or pullover for insulation if the weather cools off. Fishing in the spring and fall calls for a warm hat (that covers the ears) and warm gloves. Fingerless gloves are very popular, but I have always found them a sure way to get the tips of one’s fingers cold. I prefer to wear a full fingered glove that gives me enough dexterity to handle line. When I need to tie a knot or unhook a fish, I take the gloves off and stuff them in tops of my waders or in an inside pocket. I also carry a small towel, so that if my hands get wet, I can dry them completely before donning the gloves again.

You should carry the best quality raingear that you can afford. A breathable rain jacket also doubles as a windbreaker on blustery days. Raingear in the trunk of the car (or worse, back in the motel room) offers little protection, so choose a jacket that you are willing to pack along.

Packing the right clothes and gear allows the angler to concentrate on the fishing situation, rather than frozen fingers or the stream of cold rain dripping into one’s collar. Packing and dressing intelligently for a variety of weather conditions is an important part of fishing tactics. In next part, we discuss how to deal with a special weather condition: wind.

Montana Fly FishingOf all of the vagaries of weather, wind is probably the one most dreaded by spring creek anglers. In a game that places a premium on casting accuracy and spotting the quarry, wind can create serious problems. All the same, wind is an almost constant companion to the fly fisher, so strategies for dealing with windy conditions are an important part of angling tactics.

The first problem with wind is that for most anglers even a light breeze destroys casting accuracy. This is a particular problem in spring creek and tailwater situations because placement of the fly in a narrow feeding lane is crucial to success. A further complication is the fact that drag may be caused not only by current acting on the leader and fly, but also by wind pushing the fly and tippet across these currents.

A wind ruffle on the surface of the water also makes fish much harder to see, even with the aid of polarized sunglasses. Even experienced spring creek anglers may find that they spook more fish because they don’t see them until the fish are scurrying for the cover of a weed bed.

Wind can also indicate other weather changes that have adverse effects on fishing. Summer afternoon winds caused by temperature gradients can be annoying, but the fish are still willing to eat in these conditions if the angler can get the fly to the target. Winds caused by large scale barometric pressure changes as a storm front moves in can put a complete damper on the feeding activity of the fish.

My experience is that wind also diminishes hatch activity, although it is not clear whether the insects are reacting to changes in air pressure or sudden changes in light intensity (from wind chop on the surface of the water). It is not unusual to see the start of a good hatch and then watch the activity dissipate as the wind picks up. Similarly, evening falls of mayfly spinners are dependent on gradient winds dropping in the evening to allow the bugs enough mobility to form a mating swarm — if the wind stays up, the spinner fall just won’t happen.

On the other hand, anglers should recognize that wind — in small doses — can be an ally. In extremely flat water, a breeze can produce a riffle where one didn’t exist before. The broken surface of the water in wind chop prevents the fish from getting a good a look at the fly or its drift, and although fish are harder to spot in these conditions, it is also harder for the fish to spot the angler. If there is decent hatch activity in the wind, the fish grow accustomed to the hatching insects skittering across the surface, movement that is mimicked by the drag of a less than perfect drift. The fish also recognize that hatching bugs in these conditions are often ripped away from them quickly, so they may become more aggressive in their feeding habits, slashing at the insects (and your artificial fly) before it can get away.

Tackle Selection for Windy Conditions

Some of the problems created by wind can be alleviated by proper tackle selection. One strategy is to pack a heavier rod and line as a backup for use in windy conditions. If your standard rod for spring creek fishing is a 3-weight, think about keeping a stronger 4- or 5-weight in reserve for windy days. The delivery of the heavier line is not a problem in wind chop, and most casters will find the extra line mass will help carry the fly accurately to the target.

Even though most anglers don’t carry a variety of floating lines for different conditions, some line designs are a handicap in the wind. Long front tapers — often found on “spring creek” lines — provide a more delicate presentation, but a line with a shorter front taper is a definite asset in transferring energy to the leader and getting the fly to the target when wind is a factor.

Although rods and lines may be more glamorous, a well-designed leader is the most important piece of tackle for presenting a fly in windy conditions. In particular, a stiffer butt section is critical for transferring energy from the line down the leader. Many spring creek anglers are enamored of soft-butted leaders (either knotless or braided butt designs) with extra long tippets. These leaders help produce a drag-free drift by failing to transfer energy through the length of the leader, which dumps slack tippet material into the cast. This works well with downstream presentations when a reach cast or reach mend can skate the fly across several current lines and leave it in the fish’s feeding lane, but accuracy is nearly impossible when the caster tries to drive one of these leaders into or across the wind.

Hand-tied leaders offer the advantage of combining different leader materials to get the best of both worlds — a stiff butt section for positive turnover and a soft tippet for a better drift. In windy conditions, don’t be afraid to shorten the tippet. A shorter tippet will transfer energy more efficiently, and although it will present the fly faster and “harder”, this is usually hidden by surface chop.

Casting and Presentation in the Wind

These notions of how wind affects fishing point toward several basic fishing strategies of casting and presentation. The first is to leave the dictum to “fish fine and far off” for calmer days. Since accuracy is at a premium, get as close as possible and let the wind hide your approach.

Wind velocity is always lowest right above the surface of the water, so try to drive the forward cast low and allow the loop to unroll just above the target.

Wind velocity is always lowest right above the surface of the water, so try to drive the forward cast low and allow the loop to unroll just above the target. Driving the forward cast too high puts the loop into a zone with more wind and also gives the wind more time to act on the cast before it can drop the fly to the target.

If the wind is blowing directly upstream, don’t try to present the fly downstream with a reach cast. You may be able to make the reach with the line and butt of the leader, but the wind will invariably kick the tippet and fly back upstream, leaving a downstream belly in the tippet that will cause drag on every drift. With upstream wind, rely on a traditional upstream cast, and hope that surface chop will hide small amounts of drag that come with this style of presentation.

If the wind is blowing downstream, you may be able to make a reach cast by simply holding the line out in the wind (on a slight upstream angle) and hovering the fly slightly above the target. Drop the rod tip quickly to put the line, leader, and fly on the fish’s feeding lane, and then reach downstream to allow the fly to drift naturally.

Extremely windy conditions will frustrate even the best caster, and there are times it is important to recognize that discretion is the better part of valor—if the wind is gusting to hurricane force, it may be time to retire to the motel room to tie flies for the next day (or to a local tavern to commiserate with other disappointed anglers). But there are casting and fishing techniques that will allow an angler to minimize the effects of wind, and it’s worth trying to achieve a level of proficiency that will make a moderate breeze a nuisance, but not a total barrier to success.

MidCurrent Fly Fishing
 
Brant Oswald has worked in nearly every segment of the fly fishing industry--as a commercial fly tier, fishing school instructor/director for both Orvis and the Mel Krieger schools, travel consultant, fly shop manager, and now as a guide and outfitter in Livingston, Montana.  Brant has written for The Angler's Journal and Wild Trout Journal, and has been a contributor to Big Sky Journal, Fly Fishing Retailer, Rod & Reel, and Wild on the Fly, as well as Tight Loop and Flyfisher, both Japanese fly fishing magazines.  He now contributes regularly online, particularly at Midcurrent.com. Article copyright © 2004 by Brant K. Oswald.
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