Ridgemark climate

Ridgemark Frost Dates and Growing Season

NOAA 1991-2020 normals for Hollister 2, 6.3 km from Ridgemark, elevation 275 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Hollister 2. 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 19 and the first fall freeze around December 1, a growing season of about 287 days.

Median at 36°F
last March 27, first November 15
Median at 32°F
last February 19, first December 1
Median at 28°F
last January 16, first December 14

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 18Apr 10Apr 5Mar 31Mar 27Mar 20Mar 11Mar 4Feb 23
32°FMar 28Mar 12Mar 2Feb 25Feb 19Feb 12Feb 3Jan 25Jan 10
28°FFeb 28Feb 13Feb 2Jan 24Jan 16Jan 9Jan 1Dec 26Dec 19
24°FJan 17Jan 9Jan 4Jan 1Dec 31Dec 27Dec 21Dec 15Dec 7
20°F–––––––––
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 31Nov 3Nov 7Nov 11Nov 15Nov 19Nov 22Nov 26Dec 1
32°FNov 12Nov 19Nov 23Nov 27Dec 1Dec 3Dec 6Dec 12Dec 25
28°FNov 26Dec 1Dec 5Dec 9Dec 14Dec 19Dec 24Jan 2Jan 14
24°FDec 3Dec 10Dec 13Dec 17Dec 22Dec 28Dec 31Jan 4Jan 10
20°F–––––––––
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°F269257249242235228222215205
32°F328313304295287278271261247
28°F365360351343337331322312289
24°F365365365365365365362352339
20°F365365365365365365365365365
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
83% of years
24°F or colder
34% of years
20°F or colder
5% of years
16°F or colder
0% 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
2,739
Cooling degree days, base 65°F
412
Growing degree days, base 40°F
6,804
Growing degree days, base 45°F
5,026
Growing degree days, base 50°F
3,401
Growing degree days, base 55°F
2,056
Growing degree days, base 60°F
1,050

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January491047
February382077
March3391149
April2537210
May15627337
June6856438
July3184518
August17107555
September3991503
October11937383
November3242149
December519037

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 6.3 km from Ridgemark. 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 USC00044025 (Hollister 2). Public domain.