Seneca climate

Seneca Frost Dates and Growing Season

NOAA 1991-2020 normals for Marseilles Lock, 12.1 km from Seneca, elevation 490 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Marseilles Lock. 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 April 27 and the first fall freeze around October 17, a growing season of about 171 days.

Median at 36°F
last May 7, first October 7
Median at 32°F
last April 27, first October 17
Median at 28°F
last April 15, first October 27

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°FMay 22May 18May 13May 10May 7May 4May 1Apr 28Apr 22
32°FMay 13May 7May 3Apr 30Apr 27Apr 23Apr 21Apr 17Apr 12
28°FMay 1Apr 26Apr 21Apr 18Apr 15Apr 12Apr 9Apr 5Apr 2
24°FApr 18Apr 12Apr 8Apr 5Apr 3Apr 1Mar 29Mar 24Mar 17
20°FApr 6Apr 1Mar 30Mar 26Mar 22Mar 19Mar 15Mar 11Mar 5
16°FMar 29Mar 23Mar 19Mar 15Mar 12Mar 9Mar 6Mar 2Feb 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°FSep 24Sep 29Oct 1Oct 5Oct 7Oct 9Oct 12Oct 15Oct 20
32°FOct 3Oct 8Oct 12Oct 14Oct 17Oct 19Oct 22Oct 25Oct 29
28°FOct 14Oct 19Oct 22Oct 24Oct 27Oct 29Nov 1Nov 4Nov 9
24°FOct 26Oct 29Nov 1Nov 3Nov 5Nov 9Nov 12Nov 16Nov 22
20°FNov 2Nov 6Nov 10Nov 14Nov 17Nov 20Nov 24Nov 28Dec 3
16°FNov 10Nov 16Nov 20Nov 24Nov 27Dec 1Dec 4Dec 8Dec 14

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°F170164159155152148143138131
32°F191184180176171168163158151
28°F215206201197194190185180173
24°F239231225221217213208203196
20°F261253248242239234230224216
16°F283274267263258254250243236

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
6,351
Cooling degree days, base 65°F
800
Growing degree days, base 40°F
5,228
Growing degree days, base 45°F
4,095
Growing degree days, base 50°F
3,084
Growing degree days, base 55°F
2,192
Growing degree days, base 60°F
1,426

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,30801
February1,08302
March859227
April4786107
May19557339
June30168588
July5251711
August8208665
September9494453
October39815164
November764025
December1,13003

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 12.1 km from Seneca. 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 USC00115372 (Marseilles Lock). Public domain.