Tully climate

Tully Frost Dates and Growing Season

NOAA 1991-2020 normals for Tully Heiberg Forest, 4.8 km from Tully, elevation 1899 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Tully Heiberg Forest. 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 5, a growing season of about 147 days.

Median at 36°F
last May 25, first September 25
Median at 32°F
last May 12, first October 5
Median at 28°F
last May 1, 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°FJun 8Jun 3May 31May 28May 25May 22May 18May 14May 9
32°FMay 28May 22May 18May 15May 12May 9May 6May 3Apr 29
28°FMay 17May 11May 7May 4May 1Apr 29Apr 25Apr 22Apr 17
24°FMay 4Apr 30Apr 26Apr 22Apr 20Apr 16Apr 13Apr 9Apr 4
20°FApr 22Apr 18Apr 14Apr 11Apr 7Apr 5Apr 3Apr 1Mar 28
16°FApr 15Apr 8Apr 5Apr 3Apr 1Mar 31Mar 27Mar 24Mar 18

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 12Sep 16Sep 20Sep 22Sep 25Sep 28Oct 1Oct 4Oct 7
32°FSep 22Sep 27Sep 30Oct 2Oct 5Oct 8Oct 11Oct 16Oct 23
28°FOct 1Oct 5Oct 10Oct 14Oct 18Oct 22Oct 27Oct 31Nov 4
24°FOct 12Oct 21Oct 26Oct 30Nov 1Nov 3Nov 6Nov 9Nov 15
20°FOct 31Nov 2Nov 6Nov 9Nov 12Nov 14Nov 17Nov 22Nov 28
16°FNov 8Nov 13Nov 15Nov 18Nov 22Nov 25Nov 29Dec 3Dec 8

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°F145137131126123118113109102
32°F167161156151147142138133124
28°F192184178173169165160155146
24°F215209204199194190186180173
20°F237230226221217214210205198
16°F254248243239235231227223216

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
7,876
Cooling degree days, base 65°F
281
Growing degree days, base 40°F
3,807
Growing degree days, base 45°F
2,819
Growing degree days, base 50°F
1,962
Growing degree days, base 55°F
1,242
Growing degree days, base 60°F
673

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,39501
February1,21900
March1,11004
April704239
May36515178
June13453374
July44104525
August6185488
September22022269
October550172
November866011
December1,20901

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 4.8 km from Tully. 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 USC00308627 (Tully Heiberg Forest). Public domain.