Browns Valley climate

Browns Valley Frost Dates and Growing Season

NOAA 1991-2020 normals for Browns Valley, 0.4 km from Browns Valley, elevation 978 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Browns Valley. 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 9 and the first fall freeze around September 28, a growing season of about 141 days.

Median at 36°F
last May 19, first September 19
Median at 32°F
last May 9, first September 28
Median at 28°F
last April 30, first October 7

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 1May 28May 24May 22May 19May 16May 14May 11May 6
32°FMay 22May 17May 15May 12May 9May 6May 4May 1Apr 28
28°FMay 12May 8May 5May 2Apr 30Apr 27Apr 24Apr 20Apr 15
24°FMay 3Apr 29Apr 25Apr 22Apr 19Apr 16Apr 13Apr 10Apr 6
20°FApr 25Apr 20Apr 17Apr 13Apr 10Apr 7Apr 5Apr 2Mar 29
16°FApr 17Apr 12Apr 8Apr 5Apr 3Apr 1Mar 29Mar 23Mar 17

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 4Sep 10Sep 13Sep 16Sep 19Sep 22Sep 24Sep 27Oct 1
32°FSep 15Sep 19Sep 22Sep 25Sep 28Sep 30Oct 2Oct 6Oct 10
28°FSep 22Sep 27Oct 1Oct 4Oct 7Oct 11Oct 14Oct 18Oct 22
24°FOct 2Oct 8Oct 13Oct 17Oct 20Oct 22Oct 25Oct 29Nov 2
20°FOct 16Oct 21Oct 24Oct 28Oct 31Nov 1Nov 4Nov 7Nov 11
16°FOct 26Oct 30Nov 2Nov 4Nov 7Nov 9Nov 12Nov 15Nov 20

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°F140134130126123119115111103
32°F158152148144141137133128123
28°F181173168164160156151145140
24°F201195190186181177172167160
20°F220213208204200196192187179
16°F239231226222218213209203197

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
8,506
Cooling degree days, base 65°F
534
Growing degree days, base 40°F
4,233
Growing degree days, base 45°F
3,259
Growing degree days, base 50°F
2,397
Growing degree days, base 55°F
1,650
Growing degree days, base 60°F
1,024

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,66100
February1,36900
March1,13503
April670141
May29526237
June63109497
July15204654
August34147578
September20044311
October590472
November1,01604
December1,46000

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 0.4 km from Browns Valley. 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 USC00211063 (Browns Valley). Public domain.