Saint Francis climate

Saint Francis Frost Dates and Growing Season

NOAA 1991-2020 normals for Allagash, 13.7 km from Saint Francis, elevation 596 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Allagash. 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 June 2 and the first fall freeze around September 15, a growing season of about 102 days.

Median at 32°F
last June 2, first September 15
Median at 28°F
last May 20, first September 29

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°F–––––––––
32°FJun 21Jun 12Jun 8Jun 4Jun 2May 30May 27May 24May 21
28°FJun 6Jun 1May 27May 23May 20May 16May 13May 9May 4
24°FMay 24May 16May 12May 9May 5May 3Apr 30Apr 28Apr 24
20°FMay 8May 3Apr 30Apr 28Apr 26Apr 23Apr 19Apr 16Apr 11
16°FApr 28Apr 24Apr 20Apr 17Apr 15Apr 12Apr 9Apr 6Apr 4

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°F–––––––––
32°FAug 29Sep 4Sep 8Sep 12Sep 15Sep 18Sep 21Sep 25Sep 30
28°FSep 13Sep 18Sep 22Sep 26Sep 29Oct 1Oct 4Oct 7Oct 13
24°FSep 26Oct 1Oct 3Oct 7Oct 11Oct 15Oct 19Oct 23Oct 29
20°FOct 9Oct 15Oct 19Oct 23Oct 27Oct 31Nov 2Nov 6Nov 11
16°FOct 23Oct 30Nov 1Nov 4Nov 7Nov 9Nov 13Nov 16Nov 22

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°F979185807570635646
32°F12311611210810299948776
28°F151143137133129124120114105
24°F179171165161156151146140130
20°F204196191187183179174168160
16°F224218213209205201197193186

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
10,148
Cooling degree days, base 65°F
147
Growing degree days, base 40°F
2,936
Growing degree days, base 45°F
2,101
Growing degree days, base 50°F
1,392
Growing degree days, base 55°F
820
Growing degree days, base 60°F
401

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,79500
February1,57500
March1,40300
April88505
May499389
June20727278
July8161445
August12143388
September34212163
October709022
November1,04102
December1,49100

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 13.7 km from Saint Francis. 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 USC00170200 (Allagash). Public domain.