Ramona climate

Ramona Frost Dates and Growing Season

NOAA 1991-2020 normals for Ramona Fire Dept, 5.1 km from Ramona, elevation 1470 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Ramona Fire Dept. 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 March 4 and the first fall freeze around December 4, a growing season of about 270 days.

Median at 36°F
last April 10, first November 19
Median at 32°F
last March 4, first December 4
Median at 28°F
last January 31, first December 19

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 28Apr 21Apr 17Apr 13Apr 10Apr 6Apr 3Mar 30Mar 17
32°FApr 10Mar 31Mar 23Mar 11Mar 4Feb 27Feb 21Feb 13Jan 29
28°FMar 1Feb 23Feb 15Feb 8Jan 31Jan 20Jan 11Dec 31Dec 23
24°FFeb 19Feb 9Jan 31Jan 20Jan 11Jan 5Dec 31Dec 26Dec 16
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 26Nov 3Nov 9Nov 14Nov 19Nov 22Nov 26Dec 1Dec 4
32°FNov 17Nov 25Nov 30Dec 2Dec 4Dec 7Dec 11Dec 14Dec 18
28°FDec 1Dec 8Dec 12Dec 16Dec 19Dec 23Dec 27Jan 2Jan 16
24°FDec 12Dec 20Dec 26Dec 30Jan 3Jan 8Jan 15Jan 31Feb 13
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°F247238231225221215210202193
32°F308296287279270262253245234
28°F361351343335327320310299286
24°F365365365365365365361350332
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
92% of years
24°F or colder
38% of years
20°F or colder
3% 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
2,036
Cooling degree days, base 65°F
1,100
Growing degree days, base 40°F
8,189
Growing degree days, base 45°F
6,377
Growing degree days, base 50°F
4,659
Growing degree days, base 55°F
3,171
Growing degree days, base 60°F
1,987

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January3821114
February3271113
March3091172
April2108253
May10440402
June20119549
July1270735
August1334798
September7236679
October6076481
November20515269
December411096

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 5.1 km from Ramona. 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 USC00047228 (Ramona Fire Dept). Public domain.