Dawson climate

Dawson Frost Dates and Growing Season

NOAA 1991-2020 normals for Madison Wwtp, 11.7 km from Dawson, elevation 1075 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Madison Wwtp. 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 3 and the first fall freeze around October 2, a growing season of about 151 days.

Median at 36°F
last May 12, first September 24
Median at 32°F
last May 3, first October 2
Median at 28°F
last April 23, 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°FMay 25May 20May 17May 14May 12May 9May 6May 4Apr 30
32°FMay 15May 11May 7May 5May 3May 1Apr 29Apr 25Apr 21
28°FMay 5May 2Apr 30Apr 26Apr 23Apr 21Apr 18Apr 14Apr 9
24°FApr 29Apr 24Apr 20Apr 18Apr 15Apr 11Apr 8Apr 5Apr 1
20°FApr 21Apr 17Apr 12Apr 9Apr 6Apr 4Apr 1Mar 29Mar 22
16°FApr 13Apr 8Apr 4Apr 2Mar 31Mar 28Mar 23Mar 19Mar 14

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 26Sep 28Oct 1Oct 6
32°FSep 20Sep 25Sep 28Sep 30Oct 2Oct 5Oct 8Oct 11Oct 15
28°FSep 29Oct 2Oct 5Oct 9Oct 12Oct 15Oct 18Oct 21Oct 26
24°FOct 7Oct 13Oct 17Oct 20Oct 23Oct 25Oct 28Oct 31Nov 4
20°FOct 17Oct 23Oct 26Oct 28Oct 31Nov 2Nov 5Nov 8Nov 13
16°FOct 27Oct 31Nov 3Nov 5Nov 8Nov 11Nov 13Nov 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°F152145142138135132128123117
32°F168162158154151147144140134
28°F190183178173169166162157152
24°F207201197193189185180175169
20°F225218214210205201197192185
16°F241234229225221217213208201

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
8,281
Cooling degree days, base 65°F
608
Growing degree days, base 40°F
4,451
Growing degree days, base 45°F
3,457
Growing degree days, base 50°F
2,570
Growing degree days, base 55°F
1,794
Growing degree days, base 60°F
1,136

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,63800
February1,35700
March1,10805
April639150
May26636269
June45139544
July10224679
August29150586
September17053344
October564586
November1,00206
December1,45400

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 11.7 km from Dawson. 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 USC00214994 (Madison Wwtp). Public domain.