Cascade Locks climate

Cascade Locks Frost Dates and Growing Season

NOAA 1991-2020 normals for Bonneville Dam, 6.1 km from Cascade Locks, elevation 62 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bonneville Dam. 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 14 and the first fall freeze around November 27, a growing season of about 257 days.

Median at 36°F
last April 15, first November 10
Median at 32°F
last March 14, first November 27
Median at 28°F
last February 14, first December 14

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 5Apr 30Apr 25Apr 20Apr 15Apr 10Apr 4Mar 31Mar 23
32°FApr 4Mar 28Mar 24Mar 19Mar 14Mar 10Mar 5Feb 28Feb 19
28°FMar 10Mar 2Feb 25Feb 19Feb 14Feb 7Jan 28Jan 14Jan 4
24°FFeb 26Feb 18Feb 11Jan 31Jan 21Jan 10Jan 6Dec 31Dec 17
20°FFeb 21Feb 12Jan 30Jan 18Jan 9Jan 6Dec 31Dec 21Dec 11
16°FFeb 13Feb 6Jan 24Jan 13Jan 7Jan 3Dec 29Dec 23Dec 13

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 24Oct 30Nov 2Nov 6Nov 10Nov 12Nov 16Nov 21Nov 27
32°FNov 8Nov 13Nov 18Nov 23Nov 27Dec 1Dec 4Dec 8Dec 15
28°FNov 21Nov 29Dec 5Dec 9Dec 14Dec 20Dec 27Jan 2Jan 13
24°FDec 1Dec 10Dec 16Dec 24Dec 30Jan 3Jan 9Jan 21Feb 10
20°FDec 7Dec 13Dec 21Dec 29Jan 3Jan 7Jan 15Jan 30Feb 16
16°FDec 11Dec 17Dec 27Dec 30Jan 4Jan 7Jan 17Feb 1Feb 11

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°F233224218212207201196190181
32°F294279271263257251245237226
28°F345332320313306299291281269
24°F365365361352342334325316305
20°F365365365365365365353343329
16°F365365365365365365365365357

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
97% of years
24°F or colder
71% of years
20°F or colder
39% of years
16°F or colder
14% 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
4,784
Cooling degree days, base 65°F
356
Growing degree days, base 40°F
4,963
Growing degree days, base 45°F
3,548
Growing degree days, base 50°F
2,407
Growing degree days, base 55°F
1,507
Growing degree days, base 60°F
821

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January82201
February66202
March600017
April427176
May25811226
June12837359
July28122560
August19130577
September9251410
October3293161
November602018
December82002

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 6.1 km from Cascade Locks. 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 USC00350897 (Bonneville Dam). Public domain.