Bronte climate

Bronte Frost Dates and Growing Season

NOAA 1991-2020 normals for Bronte 11 Nne, 17.6 km from Bronte, elevation 1997 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Bronte 11 Nne. 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 28 and the first fall freeze around November 4, a growing season of about 222 days.

Median at 36°F
last April 8, first October 28
Median at 32°F
last March 28, first November 4
Median at 28°F
last March 14, first November 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°FApr 26Apr 20Apr 16Apr 12Apr 8Apr 5Apr 2Mar 29Mar 22
32°FApr 14Apr 8Apr 4Mar 31Mar 28Mar 23Mar 18Mar 14Mar 8
28°FApr 5Mar 30Mar 22Mar 17Mar 14Mar 10Mar 7Mar 3Feb 25
24°FMar 21Mar 14Mar 9Mar 6Mar 2Feb 28Feb 24Feb 18Feb 8
20°FMar 10Mar 4Feb 28Feb 23Feb 16Feb 9Feb 4Jan 29Jan 20
16°FMar 1Feb 19Feb 10Feb 5Jan 30Jan 25Jan 18Jan 7Dec 25

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 16Oct 20Oct 23Oct 26Oct 28Oct 30Nov 1Nov 4Nov 9
32°FOct 23Oct 27Oct 31Nov 2Nov 4Nov 6Nov 10Nov 13Nov 18
28°FOct 30Nov 3Nov 6Nov 10Nov 12Nov 16Nov 20Nov 25Dec 1
24°FNov 5Nov 11Nov 15Nov 19Nov 24Nov 28Dec 2Dec 6Dec 13
20°FNov 15Nov 21Nov 28Dec 2Dec 6Dec 11Dec 19Dec 26Jan 5
16°FNov 27Dec 5Dec 13Dec 21Dec 27Jan 1Jan 8Jan 18Feb 1

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°F223215211207202197193187180
32°F244237232227222217212207200
28°F267259253248244239234228218
24°F295284278272266262256251240
20°F331320310303296288280273264
16°F365359347337331324314305292

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
99% of years
16°F or colder
86% 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
2,644
Cooling degree days, base 65°F
2,198
Growing degree days, base 40°F
8,829
Growing degree days, base 45°F
7,206
Growing degree days, base 50°F
5,722
Growing degree days, base 55°F
4,388
Growing degree days, base 60°F
3,212

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January652037
February473391
March28820242
April10492445
May21246690
June0426876
July0518983
August0504968
September7295738
October11388448
November3777154
December608152

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 17.6 km from Bronte. 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 USW00003072 (Bronte 11 Nne). Public domain.