Weston climate

Weston Frost Dates and Growing Season

NOAA 1991-2020 normals for Peru, 9.6 km from Weston, elevation 1700 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Peru. 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 16 and the first fall freeze around October 2, a growing season of about 140 days.

Median at 36°F
last May 28, first September 22
Median at 32°F
last May 16, first October 2
Median at 28°F
last May 3, first October 13

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 11Jun 6Jun 3May 31May 28May 25May 22May 19May 13
32°FMay 31May 26May 22May 19May 16May 12May 9May 6May 1
28°FMay 18May 13May 9May 6May 3May 1Apr 29Apr 25Apr 21
24°FMay 5May 1Apr 27Apr 24Apr 21Apr 19Apr 15Apr 11Apr 7
20°FApr 20Apr 16Apr 12Apr 9Apr 7Apr 5Apr 4Apr 2Mar 30
16°FApr 10Apr 6Apr 4Apr 3Apr 1Mar 31Mar 27Mar 23Mar 18

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 11Sep 14Sep 17Sep 19Sep 22Sep 24Sep 27Sep 30Oct 3
32°FSep 20Sep 25Sep 28Oct 1Oct 2Oct 4Oct 7Oct 11Oct 16
28°FOct 1Oct 4Oct 7Oct 10Oct 13Oct 17Oct 20Oct 25Oct 31
24°FOct 8Oct 14Oct 18Oct 21Oct 25Oct 29Nov 1Nov 4Nov 10
20°FOct 22Oct 27Oct 31Nov 2Nov 5Nov 8Nov 11Nov 15Nov 20
16°FNov 3Nov 7Nov 11Nov 14Nov 17Nov 20Nov 23Nov 26Dec 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°F13513012512111711411010598
32°F157152148144140136131127121
28°F182176170166162159155150144
24°F205200195190187183179174167
20°F230223219215211208204198191
16°F250244239234231227223219214

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
8,316
Cooling degree days, base 65°F
146
Growing degree days, base 40°F
3,467
Growing degree days, base 45°F
2,521
Growing degree days, base 50°F
1,702
Growing degree days, base 55°F
1,010
Growing degree days, base 60°F
477

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,48100
February1,24700
March1,15905
April749021
May3744151
June16025320
July4865482
August7839427
September24713236
October579058
November92304
December1,27100

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 9.6 km from Weston. 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 USC00436335 (Peru). Public domain.