Newcastle climate

Newcastle Frost Dates and Growing Season

NOAA 1991-2020 normals for Newcastle, 1.4 km from Newcastle, elevation 4415 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Newcastle. 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 13 and the first fall freeze around October 3, a growing season of about 143 days.

Median at 36°F
last May 23, first September 24
Median at 32°F
last May 13, first October 3
Median at 28°F
last May 1, first October 11

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 7Jun 1May 30May 27May 23May 21May 18May 15May 11
32°FMay 26May 21May 18May 15May 13May 10May 7May 4Apr 30
28°FMay 17May 12May 7May 4May 1Apr 30Apr 26Apr 22Apr 16
24°FMay 5Apr 30Apr 27Apr 24Apr 20Apr 17Apr 13Apr 9Apr 3
20°FApr 26Apr 19Apr 14Apr 10Apr 7Apr 4Apr 1Mar 27Mar 20
16°FApr 16Apr 8Apr 4Apr 1Mar 29Mar 25Mar 20Mar 13Mar 7

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 9Sep 15Sep 18Sep 21Sep 24Sep 26Sep 30Oct 4Oct 7
32°FSep 17Sep 23Sep 26Sep 30Oct 3Oct 5Oct 8Oct 11Oct 16
28°FSep 27Oct 2Oct 5Oct 8Oct 11Oct 15Oct 18Oct 21Oct 25
24°FOct 5Oct 10Oct 14Oct 17Oct 19Oct 23Oct 25Oct 29Nov 2
20°FOct 11Oct 16Oct 20Oct 23Oct 27Oct 30Nov 2Nov 6Nov 11
16°FOct 17Oct 23Oct 28Nov 1Nov 4Nov 8Nov 12Nov 16Nov 22

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°F14113512912612211711310899
32°F161155151147143139134130123
28°F182175170166162159153148141
24°F203196190185181177173168161
20°F226218212207203198193187180
16°F248239232226221216210203195

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
7,130
Cooling degree days, base 65°F
711
Growing degree days, base 40°F
4,589
Growing degree days, base 45°F
3,544
Growing degree days, base 50°F
2,641
Growing degree days, base 55°F
1,870
Growing degree days, base 60°F
1,226

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January1,25900
February1,06701
March871013
April597159
May33418210
June92101463
July13273725
August23241684
September16375381
October555394
November912010
December1,24600

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 1.4 km from Newcastle. 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 USC00486660 (Newcastle). Public domain.