The second peak of the summer for water temperatures likely occurred earlier this past week, with most lakes reaching the mid- to upper 70s for the second time this summer. The extended forecast for the Bemidji area is predicting highs in 70s and lows in the 50s most days in the near future, which would slowly begin to cool down the water in the lakes. The fall cooldown is seldom a straight line, with ups and downs along the way. It is usually a gradual trend that works in reverse of the spring, only with the lakes cooling off instead of warming up.
This past week may have been the last string of days with temperatures in the 80s for this summer. Then again, maybe not. There isn't a distinct cool down in the extended forecast yet, but temperatures are expected to moderate slightly next week with highs in the 70s, which is nearly perfect weather for most outdoor activities. The smoke in the air has been more noticeable on days with winds from a westerly direction, from fires all up and down the West Coast and Canada.
Water temperatures in the Bemidji area lakes are going up again after a week with highs in the low 80s. Most lakes now have surface temperatures in the mid-70s in the mornings, before the sun has had a chance to warm the water. The water temperatures are not high enough to cause most fish problems, but they are high enough to keep metabolism levels elevated for the fish. Everything has to eat more to keep up with the calories they are burning.
August has arrived with more summer-like weather, after a mid-summer cool down that had surface water temperatures in the lakes falling. It's a typical weather pattern for Bemidji to have a brief mid-summer cool down in late July, before more "Minnesota Hot" (anything warmer than 80 degrees) weather returns for August and early September. One benefit of the cool down was setting back the chances for a summer-kill in the lakes, by dropping surface water temperatures into the low 70s again.
The cool nights help keep water temperatures in the lakes from getting even warmer, which would increase the possibility of a summer-kill as water temperatures near their likely highs for the summer. There have been a few fish floating on the surface of the lakes recently, but a full out summer-kill on the cold water species would mean there would be tullibees and suckers floating all over the lakes and washing up on shore daily.
Surface water temperatures continue to rise, with most local lakes in the mid-70s. The most accurate time to measure water temperatures is first thing in the morning, before the sun has had a chance to warm the water. One of the best times of the year to catch both numbers of muskies and big muskies occurs during the second or third week in July, right after the first heavy algae bloom of the summer.
July usually has the highest average temperatures of the season, both on the land and in the lakes. Summer is officially here, so enjoy it while it lasts. Most lakes are now warmer than 70 degrees, with the best time to measure the surface water temperatures early in the morning, before the sun has a chance to warm the water.
The largest mayflies to hatch in the Bemidji area are the ones with the greenish tint that have been hatching recently. They are usually the last major insect hatch of the season, with minor insect hatches continuing periodically well into the fall. It has taken a long time for surface water temperatures in the lakes to rise back to the point they were a few weeks into the 2018 fishing season. Most lakes are approaching 70 degrees again, which is the point where summer fishing patterns start to kick-in on the lakes.
Today is Father’s Day, so fishing this weekend is probably on the agenda for many local families. If the weather is decent, it should be a busy weekend on the lakes in the Bemidji area. Walleye fishing has been good when the conditions are right, but it can be much slower during the day when the winds are light with clear skies.
The insect hatches have begun as the walleyes continue to spread out into the lakes. There is nothing limiting walleyes to how deep or shallow walleyes can go right now, as long as they can find enough food to eat. Different size walleyes eat different things, but when there is something bountiful like a major insect hatch going on in the lakes, fish of all sizes will be there to take advantage of the situation.