Dublin climate

Dublin Frost Dates and Growing Season

NOAA 1991-2020 normals for New Castle 3 Sw, 18.3 km from Dublin, elevation 991 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for New Castle 3 Sw. 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 173 days.

Median at 36°F
last May 6, 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 21May 16May 12May 9May 6May 3Apr 30Apr 26Apr 21
32°FMay 12May 7May 3Apr 30Apr 27Apr 23Apr 19Apr 16Apr 11
28°FMay 3Apr 28Apr 22Apr 18Apr 15Apr 11Apr 6Apr 3Mar 31
24°FApr 19Apr 14Apr 8Apr 5Apr 2Mar 31Mar 28Mar 23Mar 18
20°FApr 7Apr 2Mar 31Mar 27Mar 24Mar 20Mar 16Mar 13Mar 7
16°FMar 30Mar 24Mar 20Mar 16Mar 14Mar 11Mar 7Mar 3Feb 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 4Oct 7Oct 9Oct 12Oct 14Oct 18
32°FOct 4Oct 9Oct 12Oct 14Oct 17Oct 19Oct 21Oct 25Oct 28
28°FOct 13Oct 18Oct 21Oct 24Oct 27Oct 29Nov 1Nov 4Nov 8
24°FOct 23Oct 29Nov 1Nov 3Nov 6Nov 9Nov 13Nov 17Nov 25
20°FNov 3Nov 7Nov 12Nov 16Nov 19Nov 24Nov 29Dec 3Dec 9
16°FNov 13Nov 19Nov 23Nov 28Dec 1Dec 4Dec 8Dec 14Dec 21

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°F172166161157153149145139132
32°F192186182177173169165160151
28°F216208203199194191185180173
24°F241232226221217214210204198
20°F266257251245240236231224218
16°F288279273266261256251245236

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
6,018
Cooling degree days, base 65°F
737
Growing degree days, base 40°F
5,279
Growing degree days, base 45°F
4,103
Growing degree days, base 50°F
3,058
Growing degree days, base 55°F
2,144
Growing degree days, base 60°F
1,366

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,22102
February1,01604
March826133
April4547122
May18458353
June32164582
July7225684
August13181634
September9987441
October38213169
November726031
December1,05905

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 18.3 km from Dublin. 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 USC00126164 (New Castle 3 Sw). Public domain.