Pratt climate

Pratt Frost Dates and Growing Season

NOAA 1991-2020 normals for London Locks, 2.2 km from Pratt, elevation 632 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for London Locks. 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 7 and the first fall freeze around November 4, a growing season of about 209 days.

Median at 36°F
last April 22, first October 27
Median at 32°F
last April 7, first November 4
Median at 28°F
last March 27, first November 14

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 8May 2Apr 29Apr 25Apr 22Apr 20Apr 16Apr 13Apr 8
32°FApr 23Apr 18Apr 15Apr 10Apr 7Apr 5Apr 2Mar 31Mar 26
28°FApr 9Apr 4Apr 1Mar 30Mar 27Mar 22Mar 19Mar 15Mar 9
24°FMar 29Mar 25Mar 19Mar 16Mar 12Mar 8Mar 4Feb 28Feb 22
20°FMar 18Mar 14Mar 9Mar 5Mar 1Feb 27Feb 22Feb 14Feb 8
16°FMar 12Mar 5Feb 28Feb 24Feb 17Feb 12Feb 7Feb 1Jan 22

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 13Oct 18Oct 21Oct 24Oct 27Oct 29Oct 31Nov 3Nov 7
32°FOct 24Oct 28Oct 31Nov 1Nov 4Nov 6Nov 9Nov 11Nov 16
28°FNov 1Nov 6Nov 9Nov 11Nov 14Nov 17Nov 21Nov 25Dec 1
24°FNov 12Nov 16Nov 21Nov 25Nov 29Dec 1Dec 5Dec 10Dec 19
20°FNov 23Nov 30Dec 3Dec 9Dec 14Dec 19Dec 23Dec 28Jan 4
16°FDec 7Dec 16Dec 22Dec 26Dec 30Jan 2Jan 8Jan 14Jan 22

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°F204197192188185181178173167
32°F227221217213209205201195188
28°F255247242237232228224220213
24°F284274269262258253247241233
20°F314305298292286280274267256
16°F337328322315309306300293283

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
99% 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
4,471
Cooling degree days, base 65°F
1,084
Growing degree days, base 40°F
6,364
Growing degree days, base 45°F
5,000
Growing degree days, base 50°F
3,794
Growing degree days, base 55°F
2,743
Growing degree days, base 60°F
1,841

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January95008
February78009
March632158
April30514208
May11573427
June12210648
July0323787
August1295760
September34146563
October25722255
November563157
December823015

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 2.2 km from Pratt. 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 USC00465365 (London Locks). Public domain.