Salem climate

Salem Frost Dates and Growing Season

NOAA 1991-2020 normals for Salem 5NE, 6.9 km from Salem, elevation 1594 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Salem 5NE. 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 7 and the first fall freeze around September 29, a growing season of about 144 days.

Median at 36°F
last May 16, first September 21
Median at 32°F
last May 7, first September 29
Median at 28°F
last April 29, first October 8

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 27May 23May 20May 18May 16May 13May 12May 9May 5
32°FMay 19May 15May 12May 10May 7May 5May 2Apr 30Apr 25
28°FMay 11May 7May 4May 1Apr 29Apr 26Apr 23Apr 19Apr 14
24°FMay 2Apr 28Apr 25Apr 21Apr 18Apr 15Apr 12Apr 8Apr 4
20°FApr 24Apr 19Apr 16Apr 12Apr 9Apr 6Apr 4Mar 31Mar 25
16°FApr 16Apr 10Apr 6Apr 3Apr 1Mar 29Mar 25Mar 20Mar 14

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 8Sep 13Sep 16Sep 19Sep 21Sep 23Sep 26Sep 29Oct 2
32°FSep 17Sep 21Sep 24Sep 27Sep 29Oct 1Oct 4Oct 7Oct 13
28°FSep 25Sep 29Oct 2Oct 4Oct 8Oct 12Oct 15Oct 18Oct 22
24°FOct 3Oct 9Oct 14Oct 17Oct 20Oct 22Oct 25Oct 27Oct 31
20°FOct 15Oct 21Oct 23Oct 25Oct 28Oct 31Nov 2Nov 4Nov 9
16°FOct 24Oct 27Oct 31Nov 2Nov 4Nov 6Nov 10Nov 14Nov 19

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°F143139134131128124121117111
32°F161156151147144140137132127
28°F182176171166162158155150144
24°F201195190186182178174169162
20°F221213209204200196192187180
16°F238231225221217213208203196

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
8,053
Cooling degree days, base 65°F
588
Growing degree days, base 40°F
4,445
Growing degree days, base 45°F
3,440
Growing degree days, base 50°F
2,547
Growing degree days, base 55°F
1,771
Growing degree days, base 60°F
1,113

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,57100
February1,28601
March1,030112
April625154
May27631256
June50122522
July10217672
August26164603
September16949341
October572383
November1,00404
December1,43300

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 6.9 km from Salem. 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 USC00395360 (Salem 5NE). Public domain.