I entered freeze-up dates last fall for close to 100 Minnesota lakes in my notebook, gathered from friends and other interested people across the state.

I was only able to personally observe the freeze-up of a dozen lakes. From the bigger list, here are the 2014 freeze dates for seven lakes from scattered parts of the state:

• Lake Hendricks, Nov. 11 (at Hendricks, Lincoln County)

• Little Rock Lake, Nov. 13 (near Rice, Benton County)

• Woman Lake, Nov. 18 (at Longville, Cass County)

• Lake Mille Lacs, Nov. 20 (in Aitkin and Mille Lacs counties)

• Green Lake, Nov. 21 (at Spicer, Kandiyohi County)

• Lake Minnetonka, Nov. 27 (at Excelsior and Wayzata, Hennepin County)

• Grindstone Lake, Dec. 3 (near Sandstone, Pine County)

As the angle of the sun drops in autumn, lake water cools. As the water cools, it shrinks and becomes more dense. Once the temperature drops below 39 degrees, however, the water begins to swell, and this cooler water rises to the surface. Ice forms at 32 degrees. An ice cover will form on the first calm, freezing day or night after a particular pond or lake reaches 39 degrees in all parts.

The lake freeze-up dates I collect are shared with the Minnesota Department of Natural Resources and the state’s climatology office (climate.umn.edu). Send your information if you observe freeze-up. The date to record is the first day when at least 90 percent of a lake is frozen over and stays ice-covered. Also include the name of the lake, county and nearest city.

 

Jim Gilbert’s Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. He taught and worked as a naturalist for 50 years.