Frost Dates for 93422 — Atascadero, California

Half of springs at Paso Robles, CA see their last 32°F night by March 15; only one in ten is past it by February 12, and one in ten still has one after April 13. Planting tender crops after March 31 leaves a 30% risk of a frost on them, after April 6 20%, and after April 13 10%. The 29 days between the even-odds date and the one-in-ten date is narrower than at 52% of the 220 California stations behind this site's ZIP pages, so a fixed calendar date is a gamble here.

In fall the first 32°F night comes by November 10 in half of years, as early as October 23 one year in ten, and holds off past November 29 one year in ten. A hard freeze of 28°F follows 16 days later, around November 26; in spring the one-in-ten date for 28°F is March 4, 40 days before the 32°F one. The freeze-free season lasts 238 days in a typical year, shorter than at 71% of the 219 California stations; it reaches 275 days one year in ten and falls short of 206 one year in ten. On average 54 nights a year drop to 32°F or below. Nights of 36°F, when frost can still settle on leaves in low, open spots, continue 34 days longer, to about April 18, and return around October 27. Nights of 24°F, cold enough to damage hardier plants, come in 85% of winters and 16°F in 8%.

August is the warmest month at Paso Robles, CA, averaging 92°F by day and 53°F at night; December is the coldest at 61°F and 33°F. A freezing night is all but certain in every month from December to January (a 90% chance or more). From May to September the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 86% of years and March still brings one in 59% of years and April still brings one in 28% of years.

Warmth for growing adds up to 3,887 growing degree days a year (base 50°F), fewer than at 64% of the 283 California stations. 36% of them (1,412) have built up by the end of June, and August adds the most, 693. Precipitation totals 15.2 inches a year, most in January (3.4") and least in June (0.0"); May to September bring 4% of it.

The nearest other station, San Luis Obispo Poly, CA, 12 miles south of Atascadero and 422 feet lower, has a last frost 58 days earlier (January 16), a first frost 45 days later (December 25), a season 111 days longer.

Measurable snow is rare here: only 0 of 20 winters from 1991 to 2020 recorded 0.1 inch or more at Santa Margarita Boost, CA, 7.3 miles away, so there is no typical first-snow date to plan around.

ZIP 93422 is 11 miles from Paso Robles, CA, which stands at 730 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 2 other ZIP codes share the station; its figures are presented in full for 93446 (Paso Robles). The 2023 USDA Plant Hardiness Zone Map lists ZIP 93422 in zone 9a, the band where the coldest night of the year averaged 20 to 25°F (-6.7 to -3.9°C) over 1991–2020; a zone describes winter lows, not frost dates.