Normandy climate

Normandy Frost Dates and Growing Season

NOAA 1991-2020 normals for St Louis Lambert Intl AP, 7.5 km from Normandy, elevation 531 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for St Louis Lambert Intl AP. 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 2 and the first fall freeze around November 4, a growing season of about 215 days.

Median at 36°F
last April 13, first October 26
Median at 32°F
last April 2, first November 4
Median at 28°F
last March 23, first November 13

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°FApr 28Apr 23Apr 19Apr 16Apr 13Apr 9Apr 7Apr 3Mar 31
32°FApr 17Apr 11Apr 7Apr 5Apr 2Mar 31Mar 28Mar 24Mar 17
28°FApr 7Apr 3Mar 31Mar 27Mar 23Mar 20Mar 17Mar 12Mar 5
24°FMar 29Mar 23Mar 18Mar 15Mar 12Mar 9Mar 5Mar 1Feb 24
20°FMar 18Mar 14Mar 10Mar 7Mar 4Mar 2Feb 26Feb 20Feb 12
16°FMar 14Mar 9Mar 5Mar 1Feb 25Feb 20Feb 14Feb 9Feb 1

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 14Oct 18Oct 20Oct 23Oct 26Oct 28Oct 30Nov 2Nov 6
32°FOct 23Oct 27Oct 30Nov 1Nov 4Nov 6Nov 9Nov 12Nov 18
28°FNov 2Nov 5Nov 8Nov 11Nov 13Nov 16Nov 20Nov 24Nov 30
24°FNov 8Nov 13Nov 16Nov 20Nov 24Nov 27Dec 1Dec 5Dec 11
20°FNov 17Nov 23Nov 27Dec 1Dec 4Dec 8Dec 12Dec 17Dec 23
16°FNov 27Dec 1Dec 7Dec 11Dec 16Dec 21Dec 25Dec 29Jan 6

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°F213207202198195191187182176
32°F236228224220215211207202196
28°F258250245240236232227223216
24°F277270264259254250245239232
20°F301291284279274269264258250
16°F322311304299294288283276266

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
4,433
Cooling degree days, base 65°F
1,713
Growing degree days, base 40°F
7,173
Growing degree days, base 45°F
5,814
Growing degree days, base 50°F
4,590
Growing degree days, base 55°F
3,499
Growing degree days, base 60°F
2,541

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,02007
February793120
March576794
April26237264
May72150543
June4351796
July0476941
August1428893
September32212630
October22948308
November560381
December884014

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 7.5 km from Normandy. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USW00013994 (St Louis Lambert Intl AP). Public domain.