Littlerock climate

Littlerock Frost Dates and Growing Season

NOAA 1991-2020 normals for Pearblossom, 8.2 km from Littlerock, elevation 3101 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Pearblossom. 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 13 and the first fall freeze around December 1, a growing season of about 258 days.

Median at 36°F
last April 14, first November 16
Median at 32°F
last March 13, first December 1
Median at 28°F
last February 9, first December 12

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 9Apr 30Apr 25Apr 19Apr 14Apr 10Apr 4Mar 28Mar 14
32°FApr 17Apr 9Apr 1Mar 23Mar 13Mar 5Feb 28Feb 21Feb 10
28°FMar 18Mar 3Feb 24Feb 16Feb 9Jan 31Jan 18Jan 7Dec 30
24°FFeb 18Feb 7Jan 31Jan 21Jan 10Jan 4Dec 31Dec 23Dec 11
20°F–––––––––
16°F–––––––––

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 28Nov 4Nov 7Nov 12Nov 16Nov 20Nov 23Nov 28Dec 3
32°FNov 12Nov 18Nov 24Nov 28Dec 1Dec 4Dec 7Dec 11Dec 18
28°FNov 25Dec 1Dec 5Dec 9Dec 12Dec 18Dec 23Dec 31Jan 16
24°FDec 5Dec 11Dec 17Dec 25Dec 30Jan 2Jan 7Jan 21Feb 5
20°F–––––––––
16°F–––––––––

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°F249236228222216209202195185
32°F297284274266258251242232222
28°F352340332323312304294282265
24°F365365365365363357350339326
20°F365365365365365365365365363
16°F365365365365365365365365365

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
95% of years
24°F or colder
53% of years
20°F or colder
9% of years
16°F or colder
0% 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
2,376
Cooling degree days, base 65°F
2,139
Growing degree days, base 40°F
8,910
Growing degree days, base 45°F
7,177
Growing degree days, base 50°F
5,595
Growing degree days, base 55°F
4,232
Growing degree days, base 60°F
3,087

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January508053
February397187
March3007199
April17735317
May58156563
June7363806
July05611,026
August05431,007
September6351795
October71116511
November3028190
December550041

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 8.2 km from Littlerock. 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 USC00046773 (Pearblossom). Public domain.