Rosebud climate

Rosebud Frost Dates and Growing Season

NOAA 1991-2020 normals for Mission, 17.9 km from Rosebud, elevation 2587 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Mission. 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 9 and the first fall freeze around October 1, a growing season of about 146 days.

Median at 36°F
last May 19, first September 24
Median at 32°F
last May 9, first October 1
Median at 28°F
last April 30, 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 3May 29May 25May 22May 19May 16May 13May 11May 6
32°FMay 21May 17May 14May 11May 9May 6May 4May 1Apr 28
28°FMay 13May 9May 5May 2Apr 30Apr 28Apr 25Apr 22Apr 17
24°FMay 3Apr 29Apr 26Apr 23Apr 20Apr 18Apr 14Apr 10Apr 7
20°FApr 25Apr 20Apr 16Apr 13Apr 10Apr 7Apr 4Apr 1Mar 25
16°FApr 17Apr 11Apr 7Apr 4Apr 1Mar 29Mar 25Mar 20Mar 13

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 16Sep 19Sep 21Sep 24Sep 27Sep 29Oct 1Oct 6
32°FSep 19Sep 23Sep 27Sep 30Oct 1Oct 4Oct 7Oct 10Oct 15
28°FSep 28Oct 2Oct 5Oct 9Oct 12Oct 15Oct 18Oct 20Oct 25
24°FOct 6Oct 12Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 3
20°FOct 16Oct 21Oct 24Oct 27Oct 30Nov 2Nov 5Nov 9Nov 15
16°FOct 24Oct 29Nov 1Nov 4Nov 7Nov 10Nov 14Nov 18Nov 23

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°F145139135131127123120115109
32°F163158153149146141137133126
28°F184178172168164161156151146
24°F204197192188185180175170164
20°F226218212207203199194190183
16°F245237231226222216212205199

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
7,107
Cooling degree days, base 65°F
779
Growing degree days, base 40°F
4,792
Growing degree days, base 45°F
3,720
Growing degree days, base 50°F
2,789
Growing degree days, base 55°F
1,987
Growing degree days, base 60°F
1,315

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30501
February1,10002
March921019
April606261
May29724237
June67130515
July11294748
August19241687
September15083395
October5245107
November885018
December1,22101

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 17.9 km from Rosebud. 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 USC00395620 (Mission). Public domain.