The peak of summer has arrived.

Using pioneer records going back to 1819 at Fort Snelling, the average high temperature for July 26 is 86 degrees. That date is statistically one of our hottest days of the year in the Twin Cities.

The warmest air temperature ever recorded for the Twin Cities was 108 degrees on July 14, 1936. On July 6, 1936, the temperature rose to 114 degrees in Moorhead, Minn. On July 29, 1917, the temperature hit 114.5 degrees in Beardsley, Minn. — the hottest on record in Minnesota.

By comparison, Badwater, Calif., in Death Valley is home to the record-high temperature in North America of 134 degrees, measured on July 10, 1913.

During July, the central part of North America heats up with sunny skies and southwesterly or westerly winds. The Atlantic Ocean high-pressure systems move inland to clear the skies and diminish rainfall. All this means heat.

July is the warmest and sunniest month of the year everywhere in the Upper Midwest except for a few locations along Lake Superior.

It's interesting to note that most Minnesota lakes will rise to 80 degrees or warmer on the surface during the last part of July and into August. Lake temperatures should be taken down a foot in at least 5 feet of water to get a meaningful reading.

Jim Gilbert's Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. His observations have been part of the Minnesota Weatherguide Environment Calendars since 1977, and he is the author of five books on nature in Minnesota. He taught and worked as a naturalist for 50 years.