Bath climate

Bath Frost Dates and Growing Season

NOAA 1991-2020 normals for Bath, 2.8 km from Bath, elevation 1120 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bath. 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 12 and the first fall freeze around October 3, a growing season of about 144 days.

Median at 36°F
last May 25, first September 23
Median at 32°F
last May 12, first October 3
Median at 28°F
last May 1, first October 16

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°FJun 6Jun 2May 31May 28May 25May 22May 19May 14May 9
32°FMay 28May 23May 19May 15May 12May 9May 6May 2Apr 28
28°FMay 19May 12May 8May 4May 1Apr 29Apr 26Apr 22Apr 19
24°FMay 6Apr 30Apr 26Apr 23Apr 19Apr 17Apr 14Apr 9Apr 5
20°FApr 19Apr 15Apr 11Apr 8Apr 6Apr 4Apr 2Mar 31Mar 25
16°FApr 9Apr 5Apr 3Apr 1Mar 30Mar 27Mar 24Mar 20Mar 15

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 10Sep 15Sep 19Sep 21Sep 23Sep 27Sep 29Oct 2Oct 6
32°FSep 20Sep 25Sep 29Oct 1Oct 3Oct 6Oct 9Oct 13Oct 18
28°FOct 1Oct 5Oct 10Oct 13Oct 16Oct 20Oct 24Oct 29Nov 2
24°FOct 12Oct 19Oct 24Oct 29Nov 1Nov 3Nov 5Nov 9Nov 14
20°FOct 29Nov 2Nov 6Nov 9Nov 13Nov 15Nov 18Nov 22Nov 29
16°FNov 9Nov 15Nov 18Nov 21Nov 25Nov 28Dec 1Dec 4Dec 10

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°F140134129125121117112108101
32°F164158153149144140136131124
28°F188181175170166162157152145
24°F212205201196192187182176168
20°F237231227222219215211206199
16°F262253248243240236232228222

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
7,005
Cooling degree days, base 65°F
439
Growing degree days, base 40°F
4,339
Growing degree days, base 45°F
3,280
Growing degree days, base 50°F
2,363
Growing degree days, base 55°F
1,578
Growing degree days, base 60°F
928

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,29101
February1,13100
March1,00807
April616352
May29124233
June7587463
July20158603
August28124561
September16241335
October486394
November792014
December1,10501

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 2.8 km from Bath. 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 USC00300448 (Bath). Public domain.