Georgetown climate

Georgetown Frost Dates and Growing Season

NOAA 1991-2020 normals for Georgetown, 0.2 km from Georgetown, elevation 8520 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Georgetown. 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 September 19, a growing season of about 112 days.

Median at 36°F
last June 14, first September 8
Median at 32°F
last May 30, first September 19
Median at 28°F
last May 15, first September 30

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 29Jun 23Jun 20Jun 18Jun 14Jun 11Jun 8Jun 4May 31
32°FJun 14Jun 9Jun 5Jun 2May 30May 28May 25May 21May 17
28°FMay 31May 25May 21May 18May 15May 13May 10May 7May 3
24°FMay 18May 13May 9May 6May 4May 2Apr 30Apr 26Apr 21
20°FMay 10May 4May 1Apr 28Apr 24Apr 21Apr 17Apr 14Apr 8
16°FApr 30Apr 25Apr 21Apr 17Apr 14Apr 10Apr 5Apr 1Mar 25

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°FAug 23Aug 29Sep 2Sep 5Sep 8Sep 10Sep 13Sep 16Sep 20
32°FSep 5Sep 11Sep 14Sep 17Sep 19Sep 22Sep 24Sep 27Sep 30
28°FSep 16Sep 21Sep 25Sep 27Sep 30Oct 2Oct 5Oct 9Oct 15
24°FSep 27Oct 1Oct 5Oct 7Oct 11Oct 14Oct 17Oct 21Oct 26
20°FOct 4Oct 10Oct 13Oct 17Oct 20Oct 23Oct 27Nov 1Nov 7
16°FOct 13Oct 19Oct 23Oct 28Nov 1Nov 3Nov 7Nov 12Nov 17

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°F1049792888581777163
32°F1311251201161121081049991
28°F157150145141137134130125118
24°F178172167163160156151146138
20°F202195189185180175169163157
16°F225217211205200195191185176

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
8,312
Cooling degree days, base 65°F
41
Growing degree days, base 40°F
2,828
Growing degree days, base 45°F
1,929
Growing degree days, base 50°F
1,197
Growing degree days, base 55°F
625
Growing degree days, base 60°F
230

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,21100
February1,07800
March99800
April81303
May555055
June2446229
July8925402
August14910328
September3360154
October667026
November95901
December1,21400

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 0.2 km from Georgetown. 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 USC00053261 (Georgetown). Public domain.