Laporte climate

Laporte Frost Dates and Growing Season

NOAA 1991-2020 normals for Ft Collins, 7.1 km from Laporte, elevation 5004 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ft Collins. 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 2 and the first fall freeze around October 7, a growing season of about 157 days.

Median at 36°F
last May 12, first September 29
Median at 32°F
last May 2, first October 7
Median at 28°F
last April 20, first October 17

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 26May 21May 17May 14May 12May 10May 7May 4May 1
32°FMay 14May 10May 7May 4May 2Apr 30Apr 28Apr 24Apr 18
28°FMay 5Apr 30Apr 27Apr 23Apr 20Apr 17Apr 13Apr 9Apr 5
24°FApr 26Apr 20Apr 14Apr 9Apr 6Apr 3Apr 1Mar 28Mar 21
20°FApr 16Apr 7Apr 3Mar 31Mar 27Mar 23Mar 18Mar 14Mar 7
16°FApr 2Mar 26Mar 21Mar 17Mar 14Mar 10Mar 5Mar 1Feb 24

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 15Sep 21Sep 24Sep 27Sep 29Oct 1Oct 3Oct 6Oct 11
32°FSep 24Sep 29Oct 2Oct 5Oct 7Oct 10Oct 13Oct 16Oct 20
28°FOct 2Oct 7Oct 11Oct 14Oct 17Oct 19Oct 22Oct 25Oct 28
24°FOct 12Oct 17Oct 20Oct 23Oct 26Oct 30Nov 1Nov 3Nov 8
20°FOct 19Oct 25Oct 30Nov 2Nov 5Nov 8Nov 11Nov 15Nov 20
16°FOct 26Nov 1Nov 7Nov 11Nov 14Nov 18Nov 22Nov 24Nov 28

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°F154149145141138134131126120
32°F175169165161157154150146139
28°F198192187182179175171166159
24°F223216210206201197192186180
20°F246238232228223218213206197
16°F268260254248243237231223214

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
5,797
Cooling degree days, base 65°F
624
Growing degree days, base 40°F
4,980
Growing degree days, base 45°F
3,776
Growing degree days, base 50°F
2,747
Growing degree days, base 55°F
1,886
Growing degree days, base 60°F
1,181

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,03400
February87503
March699024
April482080
May24816258
June46115519
July4253714
August11189643
September12051387
October4591106
November771012
December1,04901

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 7.1 km from Laporte. 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 USC00053005 (Ft Collins). Public domain.