Basin climate

Basin Frost Dates and Growing Season

NOAA 1991-2020 normals for Basin, 0.3 km from Basin, elevation 3840 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Basin. 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 28 and the first fall freeze around October 10, a growing season of about 164 days.

Median at 36°F
last May 7, first September 29
Median at 32°F
last April 28, first October 10
Median at 28°F
last April 17, first October 20

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 21May 16May 12May 9May 7May 4May 2Apr 30Apr 27
32°FMay 11May 6May 3Apr 30Apr 28Apr 26Apr 23Apr 20Apr 15
28°FMay 1Apr 27Apr 23Apr 20Apr 17Apr 13Apr 9Apr 5Mar 31
24°FApr 20Apr 15Apr 9Apr 5Apr 2Mar 31Mar 26Mar 20Mar 14
20°FApr 11Apr 3Mar 30Mar 26Mar 21Mar 16Mar 13Mar 9Mar 6
16°FApr 2Mar 25Mar 19Mar 14Mar 11Mar 8Mar 5Mar 2Feb 26

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 15Sep 20Sep 23Sep 26Sep 29Oct 2Oct 4Oct 7Oct 12
32°FSep 26Oct 1Oct 4Oct 7Oct 10Oct 13Oct 15Oct 18Oct 22
28°FOct 7Oct 12Oct 15Oct 18Oct 20Oct 22Oct 24Oct 27Nov 1
24°FOct 15Oct 20Oct 23Oct 26Oct 28Oct 31Nov 2Nov 5Nov 10
20°FOct 24Oct 28Oct 31Nov 3Nov 5Nov 8Nov 11Nov 15Nov 19
16°FOct 31Nov 4Nov 7Nov 10Nov 13Nov 16Nov 19Nov 22Nov 25

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°F159154149145142138134130123
32°F182176171168164160156152144
28°F206200196191187183178174167
24°F230222217213208205199193187
20°F250243237231228223219213205
16°F264258253248244240235230222

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
6,765
Cooling degree days, base 65°F
950
Growing degree days, base 40°F
5,222
Growing degree days, base 45°F
4,099
Growing degree days, base 50°F
3,112
Growing degree days, base 55°F
2,260
Growing degree days, base 60°F
1,541

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,37600
February1,06801
March752025
April4603103
May20544321
June42168577
July4360821
August11293747
September12778411
October4944102
November91206
December1,31400

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 0.3 km from Basin. 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 USC00480540 (Basin). Public domain.