Astoria climate

Astoria Frost Dates and Growing Season

NOAA 1991-2020 normals for Astoria Rgnl AP, 5.3 km from Astoria, elevation 9 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Astoria Rgnl 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 March 26 and the first fall freeze around November 11, a growing season of about 232 days.

Median at 36°F
last April 25, first October 23
Median at 32°F
last March 26, first November 11
Median at 28°F
last February 18, first December 5

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 10May 4May 1Apr 28Apr 25Apr 21Apr 17Apr 11Apr 3
32°FApr 18Apr 9Apr 3Mar 29Mar 26Mar 20Mar 14Mar 7Feb 27
28°FMar 17Mar 6Feb 28Feb 23Feb 18Feb 13Feb 3Jan 19Dec 31
24°FFeb 21Feb 13Feb 3Jan 24Jan 11Jan 3Dec 23Dec 11Dec 2
20°FFeb 14Feb 1Jan 14Jan 3Dec 27Dec 21Dec 13Dec 9Dec 7
16°F–––––––––

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°FOct 5Oct 10Oct 16Oct 20Oct 23Oct 26Oct 30Nov 4Nov 11
32°FOct 22Oct 29Nov 2Nov 6Nov 11Nov 16Nov 22Nov 29Dec 8
28°FNov 9Nov 16Nov 24Dec 1Dec 5Dec 12Dec 25Jan 5Jan 30
24°FNov 24Dec 1Dec 7Dec 11Dec 20Jan 1Jan 11Jan 30Feb 10
20°FDec 2Dec 7Dec 11Dec 15Dec 21Dec 30Jan 7Jan 24Feb 13
16°F–––––––––

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°F209198192186181176169163156
32°F265254246240232226218211201
28°F345330318308299289279270257
24°F365365365365362347335325313
20°F365365365365365365365365347
16°F365365365365365365365365365

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
96% of years
24°F or colder
55% of years
20°F or colder
15% of years
16°F or colder
2% 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
4,960
Cooling degree days, base 65°F
22
Growing degree days, base 40°F
4,270
Growing degree days, base 45°F
2,702
Growing degree days, base 50°F
1,494
Growing degree days, base 55°F
657
Growing degree days, base 60°F
164

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January65907
February58406
March589013
April489031
May3612118
June2332219
July1405330
August1227350
September1856272
October3790113
November543028
December67706

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 5.3 km from Astoria. 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 USW00094224 (Astoria Rgnl AP). Public domain.