Weldon Spring climate

Weldon Spring Frost Dates and Growing Season

NOAA 1991-2020 normals for Weldon Spring NWS, 1.7 km from Weldon Spring, elevation 610 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Weldon Spring NWS. 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 10 and the first fall freeze around October 26, a growing season of about 199 days.

Median at 36°F
last April 22, first October 16
Median at 32°F
last April 10, first October 26
Median at 28°F
last March 31, first November 5

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 6May 2Apr 29Apr 25Apr 22Apr 19Apr 15Apr 12Apr 8
32°FApr 26Apr 20Apr 16Apr 13Apr 10Apr 7Apr 4Mar 31Mar 26
28°FApr 15Apr 8Apr 4Apr 1Mar 31Mar 27Mar 23Mar 19Mar 12
24°FApr 3Mar 30Mar 26Mar 22Mar 19Mar 15Mar 12Mar 7Mar 2
20°FMar 25Mar 19Mar 16Mar 12Mar 9Mar 6Mar 3Feb 28Feb 20
16°FMar 18Mar 13Mar 9Mar 5Mar 2Feb 28Feb 23Feb 17Feb 9

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 1Oct 6Oct 10Oct 13Oct 16Oct 18Oct 21Oct 24Oct 28
32°FOct 12Oct 17Oct 20Oct 23Oct 26Oct 29Oct 31Nov 2Nov 8
28°FOct 22Oct 28Oct 31Nov 2Nov 5Nov 8Nov 12Nov 16Nov 22
24°FNov 2Nov 6Nov 10Nov 13Nov 17Nov 21Nov 25Nov 29Dec 3
20°FNov 9Nov 15Nov 19Nov 24Nov 28Dec 1Dec 5Dec 9Dec 16
16°FNov 17Nov 25Nov 30Dec 4Dec 9Dec 13Dec 18Dec 23Dec 28

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°F196189184180176172167163155
32°F220213207203199195191186178
28°F242234229224221217213207199
24°F267259253248243238234228221
20°F288278272267262257253247240
16°F308300294288283277271264256

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
4,866
Cooling degree days, base 65°F
1,312
Growing degree days, base 40°F
6,501
Growing degree days, base 45°F
5,196
Growing degree days, base 50°F
4,025
Growing degree days, base 55°F
2,985
Growing degree days, base 60°F
2,078

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07705
February851014
March647470
April31224219
May102101466
June10264705
July0385849
August2344807
September53155553
October28132254
November599371
December931011

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 1.7 km from Weldon Spring. 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 USC00238805 (Weldon Spring NWS). Public domain.