Rosemount climate

Rosemount Frost Dates and Growing Season

NOAA 1991-2020 normals for Rosemount Rsch & Outreach Ctr, 3.3 km from Rosemount, elevation 945 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rosemount Rsch & Outreach Ctr. 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 2 and the first fall freeze around October 5, a growing season of about 155 days.

Median at 36°F
last May 12, first September 28
Median at 32°F
last May 2, first October 5
Median at 28°F
last April 22, first October 17

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

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 16Sep 20Sep 23Sep 26Sep 28Oct 1Oct 3Oct 6Oct 10
32°FSep 22Sep 28Oct 1Oct 3Oct 5Oct 9Oct 12Oct 15Oct 19
28°FOct 2Oct 6Oct 10Oct 14Oct 17Oct 20Oct 23Oct 26Oct 31
24°FOct 12Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 3Nov 7
20°FOct 23Oct 29Nov 1Nov 2Nov 4Nov 7Nov 9Nov 13Nov 18
16°FNov 1Nov 4Nov 7Nov 9Nov 12Nov 15Nov 18Nov 21Nov 26

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°F155150145141138134130126120
32°F173167162159155151147143136
28°F196189184179175172167162156
24°F214209204200196192188183177
20°F233227221217213209206202194
16°F250241237232228225221216210

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
8,121
Cooling degree days, base 65°F
551
Growing degree days, base 40°F
4,418
Growing degree days, base 45°F
3,412
Growing degree days, base 50°F
2,515
Growing degree days, base 55°F
1,732
Growing degree days, base 60°F
1,072

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,62000
February1,34500
March1,08109
April609257
May27230254
June54120516
July12201654
August26141580
September16752346
October540591
November97708
December1,41800

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 3.3 km from Rosemount. 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 USC00217107 (Rosemount Rsch & Outreach Ctr). Public domain.