Rollingstone climate

Rollingstone Frost Dates and Growing Season

NOAA 1991-2020 normals for Minnesota City Dam 5, 6.9 km from Rollingstone, elevation 670 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Minnesota City Dam 5. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around April 23 and the first fall freeze around October 16, a growing season of about 175 days.

Median at 36°F
last May 3, first October 5
Median at 32°F
last April 23, first October 16
Median at 28°F
last April 13, first October 25

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FMay 17May 12May 9May 6May 3May 1Apr 29Apr 25Apr 21
32°FMay 6May 2Apr 29Apr 26Apr 23Apr 21Apr 18Apr 14Apr 9
28°FApr 27Apr 23Apr 19Apr 16Apr 13Apr 10Apr 8Apr 4Apr 1
24°FApr 20Apr 14Apr 10Apr 7Apr 4Apr 2Mar 31Mar 28Mar 21
20°FApr 11Apr 5Apr 3Mar 31Mar 29Mar 25Mar 22Mar 17Mar 11
16°FApr 3Mar 31Mar 27Mar 23Mar 20Mar 17Mar 14Mar 10Mar 5

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FSep 23Sep 28Oct 1Oct 3Oct 5Oct 8Oct 11Oct 13Oct 18
32°FOct 2Oct 6Oct 10Oct 13Oct 16Oct 18Oct 21Oct 24Oct 29
28°FOct 12Oct 16Oct 20Oct 23Oct 25Oct 28Oct 31Nov 2Nov 7
24°FOct 20Oct 26Oct 30Nov 1Nov 4Nov 6Nov 9Nov 13Nov 19
20°FOct 31Nov 2Nov 6Nov 8Nov 11Nov 15Nov 19Nov 22Nov 27
16°FNov 6Nov 10Nov 13Nov 17Nov 20Nov 23Nov 26Nov 29Dec 5

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F173167162158155151147142136
32°F193187182178175171166161155
28°F212206202198194190186181175
24°F233225220215212208204199192
20°F250243238234229225221216209
16°F266258253249244241236232224

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
100% of years
28°F or colder
100% of years
24°F or colder
100% of years
20°F or colder
100% of years
16°F or colder
100% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
7,512
Cooling degree days, base 65°F
727
Growing degree days, base 40°F
4,799
Growing degree days, base 45°F
3,757
Growing degree days, base 50°F
2,823
Growing degree days, base 55°F
2,003
Growing degree days, base 60°F
1,300

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,53700
February1,26100
March991114
April555265
May21739304
June32159577
July4263724
August11196649
September14065381
October5004100
November91808
December1,34500

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 6.9 km from Rollingstone. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

More

Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00215488 (Minnesota City Dam 5). Public domain.