Meagher County climate

Meagher County Frost Dates and Growing Season

NOAA 1991-2020 normals for White Sulphur Springs #2, 6.1 km from Meagher County, elevation 5040 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for White Sulphur Springs #2. 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 June 4 and the first fall freeze around September 11, a growing season of about 97 days.

Median at 32°F
last June 4, first September 11
Median at 28°F
last May 18, first September 25

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°F–––––––––
32°FJun 20Jun 15Jun 10Jun 7Jun 4Jun 1May 30May 26May 21
28°FJun 1May 27May 24May 21May 18May 15May 13May 9May 5
24°FMay 18May 14May 11May 8May 5May 3Apr 30Apr 27Apr 22
20°FMay 9May 3Apr 30Apr 28Apr 25Apr 21Apr 18Apr 14Apr 8
16°FApr 30Apr 25Apr 20Apr 17Apr 13Apr 9Apr 5Apr 1Mar 24

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°F–––––––––
32°FAug 27Sep 1Sep 5Sep 8Sep 11Sep 15Sep 18Sep 22Sep 27
28°FSep 10Sep 15Sep 19Sep 22Sep 25Sep 27Oct 1Oct 3Oct 7
24°FSep 21Sep 26Sep 30Oct 1Oct 4Oct 6Oct 10Oct 14Oct 19
20°FSep 29Oct 2Oct 5Oct 10Oct 13Oct 16Oct 20Oct 24Oct 31
16°FOct 3Oct 9Oct 14Oct 18Oct 22Oct 27Nov 1Nov 3Nov 9

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°F898175706561555042
32°F1191121061019793878274
28°F149142137133128125121116108
24°F170164159155151148144139133
20°F195186181176172167162158151
16°F216208200196192187182176166

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
8,464
Cooling degree days, base 65°F
150
Growing degree days, base 40°F
3,086
Growing degree days, base 45°F
2,173
Growing degree days, base 50°F
1,429
Growing degree days, base 55°F
845
Growing degree days, base 60°F
419

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29000
February1,15500
March1,00101
April758012
May506180
June2589216
July7773461
August9360436
September3188184
October688035
November1,01903
December1,30200

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 6.1 km from Meagher County. 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 USC00248930 (White Sulphur Springs #2). Public domain.