Pitkin climate

Pitkin Frost Dates and Growing Season

NOAA 1991-2020 normals for Elizabeth, 17.4 km from Pitkin, elevation 150 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Elizabeth. 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 3 and the first fall freeze around November 25, a growing season of about 268 days.

Median at 36°F
last March 20, first November 10
Median at 32°F
last March 3, first November 25
Median at 28°F
last February 14, first December 10

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 10Apr 3Mar 30Mar 25Mar 20Mar 15Mar 10Mar 3Feb 25
32°FMar 28Mar 19Mar 14Mar 8Mar 3Feb 28Feb 23Feb 17Feb 4
28°FMar 12Mar 4Feb 27Feb 22Feb 14Feb 6Jan 31Jan 25Jan 16
24°FFeb 28Feb 19Feb 9Feb 2Jan 27Jan 21Jan 15Jan 8Dec 29
20°FFeb 19Feb 6Jan 31Jan 25Jan 18Jan 12Jan 6Jan 1Dec 25
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 27Nov 1Nov 3Nov 6Nov 10Nov 14Nov 19Nov 24Dec 1
32°FNov 3Nov 9Nov 14Nov 20Nov 25Nov 28Dec 2Dec 7Dec 15
28°FNov 18Nov 26Dec 1Dec 5Dec 10Dec 16Dec 24Jan 1Jan 11
24°FDec 5Dec 12Dec 21Dec 28Jan 1Jan 6Jan 12Jan 22Feb 2
20°FDec 15Dec 25Jan 1Jan 3Jan 7Jan 12Jan 20Feb 1Feb 8
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°F268257248242236231225218209
32°F301289281274268261254246235
28°F338328320311305297288280265
24°F365365356346339333325314302
20°F365365365365365365359349333
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
99% of years
24°F or colder
80% of years
20°F or colder
35% of years
16°F or colder
8% 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
1,794
Cooling degree days, base 65°F
2,532
Growing degree days, base 40°F
9,903
Growing degree days, base 45°F
8,166
Growing degree days, base 50°F
6,526
Growing degree days, base 55°F
5,031
Growing degree days, base 60°F
3,693

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January4826109
February32614165
March18949342
April68117500
May6280739
June0448898
July0530995
August0532996
September1384832
October64135539
November23227270
December4269141

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 17.4 km from Pitkin. 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 USC00162800 (Elizabeth). Public domain.