Westfield climate

Westfield Frost Dates and Growing Season

NOAA 1991-2020 normals for Charleston, 14.7 km from Westfield, elevation 700 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Charleston. 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 15 and the first fall freeze around October 23, a growing season of about 187 days.

Median at 36°F
last April 27, first October 12
Median at 32°F
last April 15, first October 23
Median at 28°F
last April 3, 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 15May 8May 3Apr 30Apr 27Apr 24Apr 21Apr 18Apr 13
32°FMay 3Apr 26Apr 22Apr 18Apr 15Apr 12Apr 9Apr 6Apr 1
28°FApr 20Apr 14Apr 10Apr 6Apr 3Apr 1Mar 30Mar 26Mar 20
24°FApr 10Apr 4Mar 31Mar 29Mar 25Mar 22Mar 18Mar 13Mar 6
20°FApr 1Mar 27Mar 22Mar 18Mar 14Mar 11Mar 7Mar 2Feb 25
16°FMar 25Mar 17Mar 12Mar 9Mar 5Mar 2Feb 27Feb 22Feb 12

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 29Oct 3Oct 7Oct 9Oct 12Oct 15Oct 17Oct 21Oct 25
32°FOct 9Oct 13Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
28°FOct 19Oct 24Oct 28Oct 31Nov 2Nov 4Nov 7Nov 10Nov 16
24°FNov 1Nov 4Nov 7Nov 10Nov 13Nov 16Nov 20Nov 24Dec 2
20°FNov 7Nov 12Nov 17Nov 20Nov 25Nov 29Dec 2Dec 5Dec 12
16°FNov 14Nov 20Nov 26Dec 1Dec 4Dec 8Dec 12Dec 18Dec 24

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°F185178174169165161157151143
32°F209202196191187182177172163
28°F235227222217213208203197190
24°F260253245240236231226220214
20°F280272266261255251246239231
16°F300291285280274269264257247

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
4,930
Cooling degree days, base 65°F
1,337
Growing degree days, base 40°F
6,513
Growing degree days, base 45°F
5,217
Growing degree days, base 50°F
4,056
Growing degree days, base 55°F
3,017
Growing degree days, base 60°F
2,108

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,10604
February869011
March657571
April30323225
May97116485
June9286727
July0377842
August2327790
September47167571
October27434260
November612262
December95309

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 14.7 km from Westfield. 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 USC00111436 (Charleston). Public domain.