Belmont climate

Belmont Frost Dates and Growing Season

NOAA 1991-2020 normals for Angelica, 9.8 km from Belmont, elevation 1475 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Angelica. 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 21 and the first fall freeze around September 30, a growing season of about 130 days.

Median at 36°F
last June 3, first September 17
Median at 32°F
last May 21, first September 30
Median at 28°F
last May 8, first October 9

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°FJun 20Jun 13Jun 9Jun 6Jun 3Jun 1May 29May 25May 19
32°FJun 6May 31May 29May 25May 21May 18May 14May 9May 2
28°FMay 25May 19May 15May 11May 8May 4Apr 30Apr 28Apr 23
24°FMay 14May 8May 4Apr 30Apr 27Apr 24Apr 22Apr 18Apr 12
20°FMay 2Apr 25Apr 21Apr 18Apr 15Apr 12Apr 7Apr 4Mar 31
16°FApr 16Apr 10Apr 6Apr 4Apr 2Mar 31Mar 29Mar 24Mar 19

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

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°F12311611210710399948979
32°F150144138134130125121115108
28°F175166161157153149144139132
24°F200193186182177173168163154
20°F227220214210206202196189181
16°F252245240235230227222217211

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
7,252
Cooling degree days, base 65°F
302
Growing degree days, base 40°F
4,026
Growing degree days, base 45°F
2,975
Growing degree days, base 50°F
2,074
Growing degree days, base 55°F
1,320
Growing degree days, base 60°F
718

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30301
February1,13701
March1,01409
April631146
May32119205
June10558406
July39113539
August5581491
September20328286
October523277
November803012
December1,11902

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 9.8 km from Belmont. 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 USC00300183 (Angelica). Public domain.