York climate

York Frost Dates and Growing Season

NOAA 1991-2020 normals for Clifton, 19.2 km from York, elevation 3520 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Clifton. 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 February 26 and the first fall freeze around November 23, a growing season of about 268 days.

Median at 36°F
last March 14, first November 14
Median at 32°F
last February 26, first November 23
Median at 28°F
last February 5, first December 5

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 7Mar 31Mar 24Mar 18Mar 14Mar 10Mar 6Mar 2Feb 24
32°FMar 15Mar 10Mar 6Mar 2Feb 26Feb 22Feb 17Feb 12Feb 6
28°FMar 3Feb 22Feb 15Feb 9Feb 5Feb 1Jan 29Jan 21Jan 9
24°FFeb 9Feb 2Jan 30Jan 23Jan 15Jan 9Jan 4Dec 28Dec 17
20°FFeb 2Jan 30Jan 19Jan 12Jan 8Jan 4Dec 30Dec 22Dec 13
16°F–––––––––

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 30Nov 4Nov 8Nov 11Nov 14Nov 16Nov 19Nov 21Nov 25
32°FNov 10Nov 15Nov 18Nov 21Nov 23Nov 26Nov 28Dec 1Dec 6
28°FNov 20Nov 24Nov 28Dec 1Dec 5Dec 9Dec 13Dec 18Dec 24
24°FNov 28Dec 6Dec 12Dec 16Dec 20Dec 25Dec 29Jan 5Jan 16
20°FDec 6Dec 18Dec 24Dec 30Jan 3Jan 6Jan 11Jan 20Jan 30
16°F–––––––––

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°F265257250245240235230223214
32°F296286279273268263259252244
28°F333322316308302297289282271
24°F365360352346339334328320309
20°F365365365365365365363354336
16°F365365365365365365365365365

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
86% of years
20°F or colder
35% of years
16°F or colder
6% 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
2,026
Cooling degree days, base 65°F
2,895
Growing degree days, base 40°F
10,005
Growing degree days, base 45°F
8,244
Growing degree days, base 50°F
6,621
Growing degree days, base 55°F
5,206
Growing degree days, base 60°F
3,972

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January522038
February3511103
March19820295
April6497483
May8298755
June05831,033
July06941,159
August06061,071
September0426876
October42158582
November29212197
December549029

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 19.2 km from York. 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 USC00021849 (Clifton). Public domain.