Lowell climate

Lowell Frost Dates and Growing Season

NOAA 1991-2020 normals for Lookout Pt Dam, 2 km from Lowell, elevation 712 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Lookout Pt 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 7 and the first fall freeze around November 27, a growing season of about 263 days.

Median at 36°F
last April 16, first November 9
Median at 32°F
last March 7, first November 27
Median at 28°F
last February 2, first December 16

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 9May 2Apr 28Apr 22Apr 16Apr 10Apr 3Mar 29Mar 20
32°FApr 2Mar 25Mar 18Mar 11Mar 7Feb 28Feb 23Feb 16Feb 4
28°FMar 5Feb 25Feb 17Feb 9Feb 2Jan 25Jan 12Jan 2Dec 21
24°FFeb 19Feb 12Jan 31Jan 20Jan 7Jan 1Dec 27Dec 18Dec 10
20°FFeb 8Jan 24Jan 8Dec 31Dec 28Dec 24Dec 19Dec 15Dec 10
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 19Oct 26Oct 31Nov 5Nov 9Nov 13Nov 18Nov 24Nov 29
32°FNov 1Nov 9Nov 16Nov 22Nov 27Dec 1Dec 6Dec 12Dec 21
28°FNov 18Dec 1Dec 6Dec 12Dec 16Dec 24Jan 1Jan 11Feb 1
24°FDec 3Dec 10Dec 16Dec 24Dec 30Jan 3Jan 14Jan 29Feb 12
20°FDec 7Dec 12Dec 16Dec 22Dec 26Dec 30Jan 6Jan 21Feb 1
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°F242230220212207200193186174
32°F305291280271263256248240228
28°F365349338329319310302290276
24°F365365365365365356344333316
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
90% of years
24°F or colder
50% of years
20°F or colder
19% of years
16°F or colder
5% 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
4,484
Cooling degree days, base 65°F
277
Growing degree days, base 40°F
5,050
Growing degree days, base 45°F
3,529
Growing degree days, base 50°F
2,311
Growing degree days, base 55°F
1,386
Growing degree days, base 60°F
712

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January71305
February58709
March558030
April436175
May2927193
June15124323
July31101535
August2999535
September9642396
October3144172
November548032
December73006

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 2 km from Lowell. 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 USC00355050 (Lookout Pt Dam). Public domain.