Fishing in the Hot Northern California Summer: An Angler’s Reflection

Just about wherever you live, there’s that one season. 

In northern climes when the mercury dips below freezing, most folks know better than heading out on a jaunty ten-mile hike. (During wintertime it’s also generally understood “it’s twelve oclock somewhere” pretty much all the time.) In NorCal “that one season” is summertime, when our beautiful natural home takes on all the qualities of a blast furnace on steroids. Life becomes a series of sprints between the air conditioners at work, home, stores, restaurants and the car. Does that mean we must abandon the outdoor paradise we live in? Hardly. But there’s more to think about than meets the eye.

I admit to being a fly fishing for wild trout fanatic, but my thoughts about chasing trout in the summer heat reaches well beyond folks with the same affliction. Not only do we need to be concerned about keeping ourselves safe, cool and well hydrated in the summer heat, but the hot weather also has a profound effect on the trout we pursue. A bit of trout biology is needed.

Everyone knows that fish, trout included, are cold blooded creatures. Instead of having internal thermometers hovering around 98.6 degrees like humans do, a trout’s physiology is able to adapt to different, and much colder temperatures. But the trout’s comfort level is not what concerns me. It’s their ability to breathe, extract oxygen from the water. 

So how might a fish not be able to breathe underwater; they have gills, right? Sure, but the temperature of the water greatly affects how much oxygen that water can hold. The colder the water, the more oxygen-rich. The warmer the water, the more oxygen-starved. Once water temperatures reach the high 60s, trout have a very difficult time finding the oxygen they need to breathe.

Of course not every angler is a catch and release fanatic like I am. If your purpose in fishing is to bring home a stringer of fish for dinner, go knock yourself out. But if you find yourself catching and releasing fish during the ridiculous heat of the day, you might as well harvest those fish. They’re very likely dead either way.

I’ve seen it happen. You can catch fish when it’s dreadfully hot outside and the water temperatures have inched up into the 70s. An angler lovingly releases their catch hoping that fish will double in size before being caught the next time. Only problem is, instead of heading for the bottom of the river to resume feeding, the fish has to deal with brain damage from fighting for its life in water lacking enough oxygen. The angler feels good about releasing his catch, but two hours later that fish is floating belly up downstream. The good news is, there are ways to still get your fishing fix during the hot months without causing unseen damage to the fishery.

Fishing early is your best bet. Not only is fishing usually great early in the morning, but you can almost always get several hours of fishing in before it really heats up. The place you’re fishing also comes into play.

When it’s really hot you want to avoid fishing lakes and streams in the hottest hours of the day. There are a few exceptions.

Fall River is a spring creek with plenty of icy-cold, deep water. It stays safely cold for the fish throughout the summer season. The lower Sacramento River is also kept really cold for the benefit of endangered salmon, but that also means it stays really cold for the trout too. Sections of the McCloud River are deep enough and shady enough to keep the water cold. Manzanita Lake in Lassen Volcanic National Park sits at 6,000 feet and stays plenty cool enough all summer long.

So here’s my best advice: If you just gotta’ fish during the heat of the NorCal summer, fish for bass! They are able to handle the warmer water much better than trout. Target locations where hatchery fish are stocked, and take that stringer of fish home for dinner. If you are into catch and release fishing for wild trout, haul yourself out of bed earlier than usual and get your fishing in before the real heat sets in. Fish those cooler locations mentioned above. Some anglers carry thermometers to monitor when the water gets warmer than 67-68 degrees, and they just quit fishing when it gets too warm for trout.

These are mainly meant to be tips to take care of trout you plan to release, but don’t forget to take care of yourself as well. Wear sunscreen, a hat with a brim and sunscreen. Bring plenty of liquids (not alcohol) to stay hydrated, and don’t push yourself during the heat. The idea is to quit fishing before you get too hot. And never underestimate the value of curling up in the air conditioning for a midday nap.

Chip O'Brien

Chip O'Brien is a regular contributor to California Fly Fisher and Northwest Fly Fishing magazines, and author of River Journal, Sacramento River and California's Best Fly Fishing: Premier Streams and Rivers from Northern California to the Eastern Sierra. He lived in Redding, California, for eighteen years, where he was a guide, teacher, and regional manager for CalTrout.

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