Ridgeway climate

Ridgeway Frost Dates and Growing Season

NOAA 1991-2020 normals for Dodgeville Wwtp, 11.2 km from Ridgeway, elevation 1118 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Dodgeville 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 7, a growing season of about 157 days.

Median at 36°F
last May 13, first September 29
Median at 32°F
last May 3, first October 7
Median at 28°F
last April 22, first October 18

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 30May 24May 20May 16May 13May 10May 7May 4Apr 30
32°FMay 17May 12May 9May 5May 3Apr 30Apr 27Apr 24Apr 19
28°FMay 6May 1Apr 27Apr 24Apr 22Apr 19Apr 15Apr 12Apr 8
24°FApr 25Apr 21Apr 17Apr 13Apr 10Apr 8Apr 5Apr 2Mar 29
20°FApr 15Apr 9Apr 6Apr 3Apr 1Mar 31Mar 27Mar 22Mar 16
16°FApr 5Mar 31Mar 29Mar 25Mar 21Mar 18Mar 15Mar 11Mar 7

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 18Sep 22Sep 25Sep 27Sep 29Oct 1Oct 3Oct 6Oct 11
32°FSep 25Sep 30Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20
28°FOct 3Oct 9Oct 13Oct 16Oct 18Oct 21Oct 23Oct 26Oct 30
24°FOct 14Oct 19Oct 23Oct 26Oct 29Oct 31Nov 2Nov 5Nov 11
20°FOct 26Nov 1Nov 2Nov 5Nov 8Nov 11Nov 14Nov 17Nov 22
16°FNov 3Nov 7Nov 11Nov 15Nov 17Nov 20Nov 23Nov 27Dec 3

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°F155150146142138134130125119
32°F175169165161157154150145138
28°F196190186182178174170165158
24°F219211207204201196193187181
20°F242234228224220216212208201
16°F262255249244240235231226220

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
7,541
Cooling degree days, base 65°F
529
Growing degree days, base 40°F
4,421
Growing degree days, base 45°F
3,393
Growing degree days, base 50°F
2,485
Growing degree days, base 55°F
1,702
Growing degree days, base 60°F
1,042

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,47400
February1,22200
March995010
April596257
May27928245
June57111504
July14192643
August26147586
September16845337
October517493
November90209
December1,29101

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 11.2 km from Ridgeway. 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 USC00472173 (Dodgeville Wwtp). Public domain.