Burwell climate

Burwell Frost Dates and Growing Season

NOAA 1991-2020 normals for Burwell, 1 km from Burwell, elevation 2176 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Burwell. 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 May 4 and the first fall freeze around October 5, a growing season of about 154 days.

Median at 36°F
last May 13, first September 28
Median at 32°F
last May 4, first October 5
Median at 28°F
last April 24, first October 15

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 25May 21May 18May 15May 13May 10May 8May 5May 1
32°FMay 15May 11May 8May 6May 4May 1Apr 30Apr 26Apr 21
28°FMay 6May 2Apr 30Apr 27Apr 24Apr 21Apr 18Apr 14Apr 9
24°FApr 28Apr 23Apr 19Apr 16Apr 13Apr 10Apr 7Apr 3Mar 30
20°FApr 18Apr 12Apr 9Apr 5Apr 3Mar 31Mar 28Mar 24Mar 17
16°FApr 9Apr 4Apr 1Mar 29Mar 25Mar 21Mar 16Mar 12Mar 6

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 14Sep 19Sep 23Sep 25Sep 28Sep 30Oct 2Oct 4Oct 8
32°FSep 24Sep 27Sep 30Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16
28°FOct 1Oct 5Oct 10Oct 12Oct 15Oct 17Oct 19Oct 22Oct 27
24°FOct 11Oct 15Oct 19Oct 21Oct 23Oct 26Oct 28Nov 1Nov 4
20°FOct 19Oct 24Oct 28Oct 30Nov 1Nov 3Nov 5Nov 9Nov 12
16°FOct 27Nov 1Nov 3Nov 6Nov 8Nov 11Nov 14Nov 18Nov 23

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°F153147143140136133130126120
32°F171165161158154150147141135
28°F192185180176172169165160155
24°F212205201197194189185180174
20°F232225219215211208203199191
16°F251243238233228225220214208

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
6,753
Cooling degree days, base 65°F
826
Growing degree days, base 40°F
5,018
Growing degree days, base 45°F
3,920
Growing degree days, base 50°F
2,953
Growing degree days, base 55°F
2,114
Growing degree days, base 60°F
1,407

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29600
February1,07001
March858019
April531381
May23936288
June39165576
July5302762
August13232683
September12783414
October4845117
November870011
December1,22300

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 km from Burwell. 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 USC00251345 (Burwell). Public domain.