Lolo climate

Lolo Frost Dates and Growing Season

NOAA 1991-2020 normals for Missoula 2 Ne, 17.7 km from Lolo, elevation 3420 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Missoula 2 Ne. 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 10 and the first fall freeze around October 1, a growing season of about 143 days.

Median at 36°F
last June 1, first September 19
Median at 32°F
last May 10, first October 1
Median at 28°F
last April 28, first October 12

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°FJun 24Jun 16Jun 10Jun 5Jun 1May 29May 25May 19May 12
32°FMay 28May 22May 17May 14May 10May 7May 5May 2Apr 27
28°FMay 11May 6May 3Apr 30Apr 28Apr 24Apr 21Apr 17Apr 12
24°FApr 28Apr 22Apr 17Apr 13Apr 8Apr 3Mar 31Mar 26Mar 19
20°FApr 9Apr 1Mar 28Mar 22Mar 18Mar 13Mar 9Mar 4Feb 28
16°FMar 22Mar 15Mar 11Mar 7Mar 3Mar 1Feb 26Feb 21Feb 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 3Sep 9Sep 12Sep 15Sep 19Sep 22Sep 25Sep 28Oct 2
32°FSep 16Sep 22Sep 26Sep 28Oct 1Oct 3Oct 6Oct 10Oct 15
28°FSep 28Oct 2Oct 5Oct 9Oct 12Oct 15Oct 18Oct 21Oct 25
24°FOct 7Oct 13Oct 19Oct 21Oct 24Oct 28Oct 31Nov 4Nov 10
20°FOct 18Oct 24Oct 28Nov 1Nov 4Nov 8Nov 12Nov 18Nov 24
16°FOct 24Oct 31Nov 5Nov 10Nov 14Nov 20Nov 23Nov 28Dec 5

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°F132124119114109104999383
32°F161154150147143139135128120
28°F188181174171167163159154148
24°F226216209203198193187181173
20°F260250243236230226220213204
16°F286275268262256250244237227

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
7,183
Cooling degree days, base 65°F
340
Growing degree days, base 40°F
3,782
Growing degree days, base 45°F
2,771
Growing degree days, base 50°F
1,932
Growing degree days, base 55°F
1,245
Growing degree days, base 60°F
716

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,18000
February96700
March82902
April603031
May3586159
June17731310
July41154578
August49126543
September22222267
October617040
November93901
December1,20100

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 17.7 km from Lolo. 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 USC00245735 (Missoula 2 Ne). Public domain.