Dundee climate

Dundee Frost Dates and Growing Season

NOAA 1991-2020 normals for Rex 1 S, 8.1 km from Dundee, elevation 515 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Rex 1 S. 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 March 21 and the first fall freeze around November 22, a growing season of about 241 days.

Median at 36°F
last April 21, first November 3
Median at 32°F
last March 21, first November 22
Median at 28°F
last February 15, first December 10

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 6May 1Apr 28Apr 26Apr 21Apr 16Apr 11Apr 5Mar 30
32°FApr 19Apr 10Apr 2Mar 28Mar 21Mar 15Mar 9Mar 1Feb 23
28°FMar 11Mar 2Feb 25Feb 20Feb 15Feb 9Feb 2Jan 21Jan 3
24°FFeb 19Feb 12Feb 1Jan 26Jan 16Jan 9Jan 1Dec 23Dec 11
20°FFeb 18Feb 7Jan 28Jan 14Jan 5Dec 31Dec 23Dec 15Dec 8
16°F–––––––––

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°FOct 20Oct 25Oct 29Oct 31Nov 3Nov 7Nov 11Nov 16Nov 22
32°FNov 4Nov 9Nov 12Nov 17Nov 22Nov 25Nov 29Dec 4Dec 12
28°FNov 15Nov 25Dec 1Dec 6Dec 10Dec 16Dec 22Dec 30Jan 12
24°FDec 1Dec 7Dec 12Dec 19Dec 27Jan 1Jan 9Jan 22Feb 7
20°FDec 6Dec 13Dec 19Dec 27Jan 1Jan 6Jan 15Feb 1Feb 16
16°F–––––––––

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°F224216209204198193188181172
32°F275263255248241234228221211
28°F343330318308301292284274260
24°F365365365359350341333322308
20°F365365365365365365363350338
16°F365365365365365365365365365

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
97% of years
24°F or colder
70% of years
20°F or colder
30% of years
16°F or colder
8% 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
4,712
Cooling degree days, base 65°F
364
Growing degree days, base 40°F
5,000
Growing degree days, base 45°F
3,549
Growing degree days, base 50°F
2,381
Growing degree days, base 55°F
1,484
Growing degree days, base 60°F
817

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January76902
February62907
March564030
April435377
May27311217
June14239347
July26124562
August21131575
September10153403
October3544142
November597018
December80102

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 8.1 km from Dundee. 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 USC00357127 (Rex 1 S). Public domain.