Burlington climate

Burlington Frost Dates and Growing Season

NOAA 1991-2020 normals for John Redmond Lake, 6.7 km from Burlington, elevation 1092 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for John Redmond Lake. 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 April 11 and the first fall freeze around October 26, a growing season of about 199 days.

Median at 36°F
last April 22, first October 18
Median at 32°F
last April 11, first October 26
Median at 28°F
last April 2, first November 4

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

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°F199193187182178173168163156
32°F219212206202199194189183176
28°F240232226221217212208202194
24°F258250244240235230225219212
20°F276269264259254248244239230
16°F299289282276272267262255248

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
4,839
Cooling degree days, base 65°F
1,527
Growing degree days, base 40°F
6,761
Growing degree days, base 45°F
5,451
Growing degree days, base 50°F
4,270
Growing degree days, base 55°F
3,223
Growing degree days, base 60°F
2,309

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,07902
February853012
March626475
April30523224
May95111484
June8303745
July0448913
August1410874
September47191595
October26335278
November608263
December95506

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 6.7 km from Burlington. 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 USC00144104 (John Redmond Lake). Public domain.