Boscobel climate

Boscobel Frost Dates and Growing Season

NOAA 1991-2020 normals for Boscobel AP, 3.3 km from Boscobel, elevation 672 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Boscobel AP. 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 155 days.

Median at 36°F
last May 14, first September 29
Median at 32°F
last May 3, first October 7
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 28May 24May 21May 17May 14May 11May 8May 5Apr 30
32°FMay 18May 13May 10May 6May 3Apr 30Apr 28Apr 24Apr 19
28°FMay 8May 2Apr 28Apr 25Apr 22Apr 19Apr 16Apr 12Apr 7
24°FApr 27Apr 21Apr 17Apr 14Apr 10Apr 7Apr 5Apr 2Mar 28
20°FApr 16Apr 9Apr 5Apr 2Apr 1Mar 29Mar 25Mar 20Mar 14
16°FApr 3Mar 31Mar 27Mar 22Mar 19Mar 16Mar 13Mar 10Mar 5

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 17Sep 21Sep 24Sep 27Sep 29Oct 1Oct 4Oct 6Oct 11
32°FSep 25Sep 29Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20
28°FOct 4Oct 8Oct 12Oct 15Oct 17Oct 20Oct 23Oct 26Oct 31
24°FOct 13Oct 19Oct 22Oct 25Oct 27Oct 30Nov 1Nov 5Nov 10
20°FOct 25Oct 30Nov 2Nov 4Nov 7Nov 10Nov 13Nov 16Nov 23
16°FNov 4Nov 7Nov 12Nov 15Nov 18Nov 21Nov 24Nov 28Dec 2

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°F154147143140136132129124118
32°F176169164159155152148144138
28°F198190185181177173168163157
24°F220212207203200195191185178
20°F244235230225222217212207200
16°F263256251247243238234230222

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
6,877
Cooling degree days, base 65°F
738
Growing degree days, base 40°F
4,955
Growing degree days, base 45°F
3,862
Growing degree days, base 50°F
2,891
Growing degree days, base 55°F
2,047
Growing degree days, base 60°F
1,324

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,41200
February1,15501
March901220
April508488
May21243311
June34155571
July6248707
August12204657
September12874402
October4618121
November830014
December1,22001

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 Boscobel. 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 USW00094994 (Boscobel AP). Public domain.