Port Austin climate

Port Austin Frost Dates and Growing Season

NOAA 1991-2020 normals for Port Austin Wwtp, 1.9 km from Port Austin, elevation 605 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Port Austin 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 4 and the first fall freeze around October 26, a growing season of about 172 days.

Median at 36°F
last May 16, first October 9
Median at 32°F
last May 4, first October 26
Median at 28°F
last April 21, first November 7

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 31May 25May 22May 18May 16May 12May 9May 6May 1
32°FMay 19May 14May 10May 7May 4May 1Apr 28Apr 25Apr 20
28°FMay 5May 1Apr 27Apr 24Apr 21Apr 19Apr 17Apr 13Apr 8
24°FApr 23Apr 18Apr 16Apr 13Apr 9Apr 6Apr 3Apr 1Mar 27
20°FApr 12Apr 7Apr 4Apr 2Mar 31Mar 28Mar 24Mar 20Mar 14
16°FApr 1Mar 29Mar 25Mar 21Mar 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 26Sep 30Oct 3Oct 6Oct 9Oct 13Oct 16Oct 21Oct 26
32°FOct 7Oct 14Oct 19Oct 23Oct 26Oct 29Nov 1Nov 3Nov 8
28°FOct 25Oct 30Nov 1Nov 4Nov 7Nov 10Nov 12Nov 16Nov 21
24°FNov 3Nov 8Nov 12Nov 16Nov 19Nov 22Nov 25Nov 28Dec 3
20°FNov 15Nov 20Nov 23Nov 26Nov 29Dec 2Dec 5Dec 10Dec 17
16°FNov 24Nov 29Dec 3Dec 6Dec 10Dec 14Dec 18Dec 22Dec 27

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°F167159154149145141137131125
32°F191185180176172168163158150
28°F218210205201197193189184178
24°F244236231226222217213209202
20°F267259254249244240236231224
16°F286279273269264260256250244

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
7,314
Cooling degree days, base 65°F
404
Growing degree days, base 40°F
4,112
Growing degree days, base 45°F
3,094
Growing degree days, base 50°F
2,214
Growing degree days, base 55°F
1,464
Growing degree days, base 60°F
850

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30500
February1,18400
March1,06706
April695032
May36218179
June11677413
July27149587
August33116549
September15939335
October4666101
November786012
December1,11600

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 1.9 km from Port Austin. 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 USC00206662 (Port Austin Wwtp). Public domain.