Waterville climate

Waterville Frost Dates and Growing Season

NOAA 1991-2020 normals for Waterville, 0.7 km from Waterville, elevation 2664 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Waterville. 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 14 and the first fall freeze around October 1, a growing season of about 140 days.

Median at 36°F
last June 6, first September 19
Median at 32°F
last May 14, first October 1
Median at 28°F
last April 29, first October 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°FJun 27Jun 19Jun 14Jun 10Jun 6Jun 2May 29May 23May 16
32°FJun 4May 29May 22May 18May 14May 10May 5May 2Apr 28
28°FMay 15May 9May 4May 1Apr 29Apr 26Apr 23Apr 20Apr 15
24°FMay 1Apr 24Apr 19Apr 15Apr 12Apr 9Apr 5Mar 31Mar 25
20°FApr 11Apr 5Mar 31Mar 27Mar 21Mar 17Mar 13Mar 9Mar 5
16°FMar 22Mar 16Mar 12Mar 9Mar 6Mar 4Mar 1Feb 26Feb 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 2Sep 9Sep 13Sep 16Sep 19Sep 21Sep 24Sep 27Sep 30
32°FSep 18Sep 23Sep 27Sep 29Oct 1Oct 3Oct 6Oct 8Oct 14
28°FSep 30Oct 3Oct 6Oct 9Oct 12Oct 14Oct 17Oct 21Oct 25
24°FOct 8Oct 13Oct 17Oct 20Oct 22Oct 25Oct 27Oct 31Nov 5
20°FOct 17Oct 22Oct 26Oct 29Nov 1Nov 4Nov 8Nov 13Nov 19
16°FOct 23Oct 29Nov 3Nov 8Nov 11Nov 15Nov 20Nov 25Dec 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°F129122115110105100948778
32°F161154148144140135129122112
28°F185177172168164161156151145
24°F216207201197193188182177170
20°F248240233228223218213207199
16°F274265259254248242237230223

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
7,533
Cooling degree days, base 65°F
353
Growing degree days, base 40°F
3,768
Growing degree days, base 45°F
2,783
Growing degree days, base 50°F
1,949
Growing degree days, base 55°F
1,257
Growing degree days, base 60°F
724

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,27000
February1,04700
March88102
April608030
May3539166
June18535305
July49147563
August48130547
September19933294
October611143
November99300
December1,29100

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 0.7 km from Waterville. 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 USC00459012 (Waterville). Public domain.