Grimsley climate

Grimsley Frost Dates and Growing Season

NOAA 1991-2020 normals for Allardt, 16 km from Grimsley, elevation 1645 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Allardt. 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 17 and the first fall freeze around October 23, a growing season of about 188 days.

Median at 36°F
last May 2, first October 14
Median at 32°F
last April 17, first October 23
Median at 28°F
last April 2, first November 2

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 18May 13May 8May 5May 2Apr 30Apr 25Apr 21Apr 14
32°FMay 7Apr 30Apr 26Apr 21Apr 17Apr 13Apr 9Apr 6Apr 1
28°FApr 22Apr 14Apr 9Apr 5Apr 2Mar 31Mar 28Mar 24Mar 18
24°FApr 8Apr 2Mar 30Mar 26Mar 23Mar 19Mar 16Mar 10Mar 3
20°FMar 30Mar 25Mar 19Mar 15Mar 11Mar 6Mar 1Feb 25Feb 16
16°FMar 20Mar 14Mar 7Mar 2Feb 27Feb 22Feb 15Feb 9Feb 2

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°FOct 3Oct 6Oct 9Oct 11Oct 14Oct 17Oct 19Oct 22Oct 25
32°FOct 9Oct 14Oct 18Oct 21Oct 23Oct 25Oct 28Oct 31Nov 4
28°FOct 19Oct 24Oct 28Oct 31Nov 2Nov 4Nov 8Nov 12Nov 17
24°FNov 1Nov 4Nov 7Nov 9Nov 13Nov 15Nov 18Nov 23Nov 28
20°FNov 7Nov 12Nov 16Nov 20Nov 23Nov 27Dec 1Dec 6Dec 13
16°FNov 16Nov 23Nov 27Dec 2Dec 6Dec 12Dec 17Dec 25Jan 2

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°F186179174169165161157152145
32°F210202197193188184179173164
28°F235227221217213208204198190
24°F261252245240235231227221214
20°F289278271265259253248242234
16°F315306299292285280275267255

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
4,327
Cooling degree days, base 65°F
892
Growing degree days, base 40°F
6,290
Growing degree days, base 45°F
4,887
Growing degree days, base 50°F
3,645
Growing degree days, base 55°F
2,564
Growing degree days, base 60°F
1,644

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January907015
February717021
March570285
April28616228
May12061412
June17170603
July2265728
August5240701
September53116514
October27219248
November565168
December814022

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 16 km from Grimsley. 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 USC00400081 (Allardt). Public domain.