Bells climate

Bells Frost Dates and Growing Season

NOAA 1991-2020 normals for Alamo 1 N, 10 km from Bells, elevation 330 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Alamo 1 N. 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 March 28 and the first fall freeze around November 4, a growing season of about 220 days.

Median at 36°F
last April 7, first October 25
Median at 32°F
last March 28, first November 4
Median at 28°F
last March 16, first November 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°FApr 22Apr 18Apr 14Apr 10Apr 7Apr 5Apr 2Mar 29Mar 23
32°FApr 12Apr 7Apr 4Apr 1Mar 28Mar 25Mar 21Mar 17Mar 11
28°FApr 3Mar 28Mar 22Mar 19Mar 16Mar 12Mar 8Mar 3Feb 26
24°FMar 20Mar 15Mar 11Mar 7Mar 3Feb 28Feb 24Feb 18Feb 9
20°FMar 12Mar 5Feb 28Feb 24Feb 18Feb 13Feb 7Feb 1Jan 26
16°FMar 2Feb 22Feb 15Feb 8Feb 3Jan 31Jan 28Jan 20Jan 11

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 12Oct 16Oct 20Oct 23Oct 25Oct 27Oct 30Nov 2Nov 6
32°FOct 22Oct 26Oct 29Nov 1Nov 4Nov 6Nov 9Nov 13Nov 20
28°FNov 1Nov 5Nov 8Nov 12Nov 15Nov 19Nov 23Nov 28Dec 4
24°FNov 11Nov 16Nov 21Nov 25Nov 29Dec 2Dec 6Dec 12Dec 22
20°FNov 22Nov 30Dec 4Dec 9Dec 17Dec 23Dec 29Jan 4Jan 14
16°FDec 6Dec 15Dec 25Jan 1Jan 5Jan 10Jan 15Jan 20Jan 30

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°F219212208204200197192186179
32°F244236230225220216212207200
28°F271262256251245241236230220
24°F302292285279273267260254246
20°F330322314307301296289281269
16°F364348338333329322314306298

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
93% 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
3,652
Cooling degree days, base 65°F
1,680
Growing degree days, base 40°F
7,587
Growing degree days, base 45°F
6,115
Growing degree days, base 50°F
4,781
Growing degree days, base 55°F
3,593
Growing degree days, base 60°F
2,558

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January843124
February656139
March4768130
April20446315
May49167583
June1348796
July0439904
August1400865
September21216645
October19050339
November4694107
December741135

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 10 km from Bells. 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 USC00400049 (Alamo 1 N). Public domain.