Glasgow climate

Glasgow Frost Dates and Growing Season

NOAA 1991-2020 normals for Glasgow Intl AP, 2.2 km from Glasgow, elevation 2285 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Glasgow Intl AP. 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 6 and the first fall freeze around September 30, a growing season of about 145 days.

Median at 36°F
last May 16, first September 23
Median at 32°F
last May 6, first September 30
Median at 28°F
last April 26, first October 9

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 30May 25May 22May 19May 16May 14May 11May 9May 5
32°FMay 18May 14May 11May 9May 6May 4May 1Apr 29Apr 24
28°FMay 8May 4May 1Apr 29Apr 26Apr 24Apr 21Apr 17Apr 13
24°FApr 30Apr 26Apr 22Apr 19Apr 16Apr 13Apr 10Apr 7Apr 2
20°FApr 21Apr 16Apr 12Apr 9Apr 6Apr 3Apr 1Mar 27Mar 19
16°FApr 13Apr 6Apr 3Apr 1Mar 28Mar 24Mar 19Mar 13Mar 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 15Sep 19Sep 21Sep 23Sep 25Sep 27Sep 30Oct 4
32°FSep 17Sep 22Sep 25Sep 28Sep 30Oct 3Oct 5Oct 9Oct 13
28°FSep 24Sep 30Oct 4Oct 6Oct 9Oct 12Oct 16Oct 19Oct 24
24°FOct 1Oct 8Oct 12Oct 16Oct 19Oct 21Oct 24Oct 27Nov 1
20°FOct 10Oct 16Oct 21Oct 25Oct 27Oct 31Nov 3Nov 7Nov 13
16°FOct 21Oct 27Oct 31Nov 3Nov 6Nov 9Nov 12Nov 16Nov 21

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°F143138135131127124121117111
32°F163157152148145141138133126
28°F185178172168164160156151145
24°F206199193188183179174168161
20°F227218213208203200194188179
16°F244237231226221216211205197

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
8,245
Cooling degree days, base 65°F
586
Growing degree days, base 40°F
4,288
Growing degree days, base 45°F
3,289
Growing degree days, base 50°F
2,415
Growing degree days, base 55°F
1,671
Growing degree days, base 60°F
1,058

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,56100
February1,29600
March1,03605
April607145
May31016212
June8873436
July14231682
August30216651
September20047317
October618364
November1,04304
December1,44300

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 2.2 km from Glasgow. 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 USW00094008 (Glasgow Intl AP). Public domain.