Reserve climate

Reserve Frost Dates and Growing Season

NOAA 1991-2020 normals for Reserve RS, 1.8 km from Reserve, elevation 5847 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Reserve RS. 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 30 and the first fall freeze around October 3, a growing season of about 127 days.

Median at 36°F
last June 10, first September 26
Median at 32°F
last May 30, first October 3
Median at 28°F
last May 13, first October 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°FJun 25Jun 20Jun 16Jun 13Jun 10Jun 7Jun 4May 31May 28
32°FJun 12Jun 8Jun 4Jun 1May 30May 26May 23May 18May 14
28°FJun 2May 25May 20May 17May 13May 10May 6May 3Apr 29
24°FMay 13May 9May 5May 3May 1Apr 28Apr 25Apr 22Apr 17
20°FMay 1Apr 28Apr 23Apr 20Apr 17Apr 14Apr 11Apr 7Apr 1
16°FApr 17Apr 11Apr 7Apr 3Mar 31Mar 25Mar 19Mar 14Mar 8

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 11Sep 17Sep 21Sep 24Sep 26Sep 28Oct 1Oct 2Oct 5
32°FSep 22Sep 27Sep 30Oct 1Oct 3Oct 5Oct 8Oct 11Oct 14
28°FOct 1Oct 3Oct 6Oct 9Oct 12Oct 14Oct 17Oct 20Oct 25
24°FOct 8Oct 13Oct 17Oct 20Oct 23Oct 26Oct 29Nov 1Nov 5
20°FOct 17Oct 22Oct 26Oct 30Nov 1Nov 4Nov 7Nov 13Nov 17
16°FOct 26Nov 1Nov 5Nov 9Nov 13Nov 16Nov 19Nov 23Nov 29

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°F124118113110107102979286
32°F147140135131127123119114107
28°F170163158153150146142137130
24°F193186181177173169165161154
20°F217211205201196191187182176
16°F251243236231226221216210200

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
4,694
Cooling degree days, base 65°F
605
Growing degree days, base 40°F
5,394
Growing degree days, base 45°F
4,023
Growing degree days, base 50°F
2,877
Growing degree days, base 55°F
1,934
Growing degree days, base 60°F
1,182

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January86501
February70002
March598022
April407091
May21913266
June42113521
July2237701
August4178639
September6561447
October3252166
November602023
December86601

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 1.8 km from Reserve. 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 USC00297386 (Reserve RS). Public domain.