Smethport climate

Smethport Frost Dates and Growing Season

NOAA 1991-2020 normals for Port Allegany, 13.1 km from Smethport, elevation 1475 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Port Allegany. 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 15 and the first fall freeze around October 6, a growing season of about 144 days.

Median at 36°F
last May 28, first September 27
Median at 32°F
last May 15, first October 6
Median at 28°F
last May 2, first October 20

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 10Jun 5Jun 1May 30May 28May 25May 22May 18May 11
32°FMay 29May 25May 22May 19May 15May 11May 8May 3Apr 29
28°FMay 20May 14May 10May 6May 2Apr 30Apr 27Apr 24Apr 20
24°FMay 9May 3Apr 29Apr 25Apr 22Apr 19Apr 17Apr 13Apr 8
20°FApr 23Apr 18Apr 15Apr 11Apr 8Apr 6Apr 3Apr 1Mar 26
16°FApr 9Apr 5Apr 2Mar 31Mar 28Mar 25Mar 21Mar 18Mar 13

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 14Sep 20Sep 23Sep 25Sep 27Sep 29Oct 1Oct 4Oct 8
32°FSep 25Sep 29Oct 1Oct 4Oct 6Oct 9Oct 12Oct 16Oct 21
28°FOct 4Oct 9Oct 13Oct 16Oct 20Oct 23Oct 26Oct 30Nov 4
24°FOct 16Oct 22Oct 26Oct 30Nov 1Nov 4Nov 7Nov 11Nov 16
20°FOct 29Nov 3Nov 7Nov 10Nov 13Nov 15Nov 18Nov 22Nov 29
16°FNov 9Nov 13Nov 17Nov 21Nov 24Nov 28Dec 1Dec 5Dec 11

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°F142136131127123119115111104
32°F164157153149144141137132125
28°F187180176172167163158153146
24°F212206201195191187182178170
20°F239232227222218214209204195
16°F266257252247243239234228221

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
7,278
Cooling degree days, base 65°F
302
Growing degree days, base 40°F
4,045
Growing degree days, base 45°F
3,007
Growing degree days, base 50°F
2,109
Growing degree days, base 55°F
1,344
Growing degree days, base 60°F
735

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,32401
February1,14400
March1,00109
April632044
May31816210
June9959411
July35112542
August4784502
September18930299
October527282
November82208
December1,14101

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 13.1 km from Smethport. 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 USC00367103 (Port Allegany). Public domain.