Lafayette climate

Lafayette Frost Dates and Growing Season

NOAA 1991-2020 normals for Northglenn, 12.4 km from Lafayette, elevation 5407 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Northglenn. 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 11, a growing season of about 160 days.

Median at 36°F
last May 12, first October 1
Median at 32°F
last May 2, first October 11
Median at 28°F
last April 20, first October 21

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 20May 17May 14May 12May 9May 7May 4Apr 30
32°FMay 14May 9May 7May 4May 2Apr 30Apr 27Apr 23Apr 18
28°FMay 5May 1Apr 28Apr 24Apr 20Apr 18Apr 14Apr 9Apr 4
24°FApr 26Apr 20Apr 14Apr 10Apr 6Apr 3Mar 31Mar 27Mar 19
20°FApr 14Apr 6Apr 1Mar 29Mar 24Mar 20Mar 14Mar 9Mar 3
16°FApr 6Mar 29Mar 23Mar 17Mar 11Mar 7Mar 3Feb 27Feb 20

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 18Sep 23Sep 27Sep 29Oct 1Oct 4Oct 7Oct 10Oct 14
32°FSep 26Oct 1Oct 4Oct 7Oct 11Oct 13Oct 16Oct 19Oct 24
28°FOct 7Oct 11Oct 15Oct 18Oct 21Oct 24Oct 27Oct 30Nov 4
24°FOct 15Oct 21Oct 24Oct 28Oct 31Nov 2Nov 5Nov 9Nov 14
20°FOct 23Oct 29Nov 1Nov 4Nov 8Nov 11Nov 14Nov 19Nov 23
16°FOct 30Nov 5Nov 9Nov 13Nov 17Nov 21Nov 24Nov 27Dec 2

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°F159153149145142138133129122
32°F180173168164160156153149142
28°F204197190186182177173168160
24°F230221215210205200195189181
20°F252244238232227221216210201
16°F274265260253247241235226217

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
5,449
Cooling degree days, base 65°F
879
Growing degree days, base 40°F
5,509
Growing degree days, base 45°F
4,249
Growing degree days, base 50°F
3,168
Growing degree days, base 55°F
2,255
Growing degree days, base 60°F
1,494

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January97704
February84106
March681039
April4672103
May23731292
June39170581
July5315775
August8258714
September9399463
October4085154
November711033
December98304

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 12.4 km from Lafayette. 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 USC00055984 (Northglenn). Public domain.