With the earliest sunrises of the year (about 5:26 a.m. CDT), birds start singing close to 4:20 a.m. It is hummingbird nesting time. Expect lakes to be in the 70 degree F range and perfect for swimming. Sulphur shelf mushrooms brighten-up woodlands. Deer flies and stable flies are on the wing. Sight and smell enable bees to locate sources of pollen and nectar. Honey bees are busy foraging on yellow sweet clover, white Dutch clover, Russian olive and many other plants; 50 to 95 degrees is the temperature range at which they are actively pollinating. Abundant wild lupine blooms are seen in the North Shore of Lake Superior area.
Nature Notes, from the Minnesota Weatherguide Environment Calendar