USDA Hardiness Zone 9b
Frost Dates for 93420 — Arroyo Grande, California
NOAA 1991–2020 normals from Pismo Beach, CA (39 ft), 8 miles west.
Updated
A freeze (32°F) reaches Arroyo Grande in 54% of winters. When it does, the first freeze of winter comes around January 4 and the last freeze of winter around February 1; after March 13 the chance of another is under 5%.
- Last freeze
- February 1
- First freeze
- January 4
- Winters with a freeze
- 54%
- Hardiness zone
- 9b
50%, in freezing years
50%, in freezing years
32°F or below, 1991–2020
25 to 30°F (-3.9 to -1.1°C) coldest night
- First snow
- Rare
- Last snow
- Rare
- Winters with snow
- 0%
- Snow per year
- 0"
median, 1991–2020
median, 1991–2020
0 of 19 observed
NOAA normal
Frost risk by date in Arroyo Grande
In the 54% of winters that bring a 32°F night, half of winters at Pismo Beach, CA see their last 32°F night by February 1; only one in ten is past it by December 18, and one in ten still has one after March 13. Counting the winters with no freeze at all, the risk of a 32°F night after March 13 is under 5% and after February 1 27%. The 40 days between the even-odds date and the one-in-ten date is wider than at 85% 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 January 4 in half of years, as early as December 8 one year in ten, and holds off past February 27 one year in ten. A hard freeze of 28°F is less common: it came in 7% of winters. On average 2 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 28 days longer, to about March 1, and return around December 14. No night reached 24°F in 1991–2020.
| Low | 90% | 80% | 70% | 60% | 50% | 40% | 30% | 20% | 10% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F98% of yrs | Jan 7 | Jan 29 | Feb 14 | Feb 23 | Mar 1 | Mar 9 | Mar 18 | Mar 29 | Apr 12 |
| 32°F54% of yrs | Dec 18 | Dec 31 | Jan 4 | Jan 17 | Feb 1 | Feb 12 | Feb 21 | Feb 28 | Mar 13 |
| 28°F7% of yrs | too rare for a date | ||||||||
| Low | 10% | 20% | 30% | 40% | 50% | 60% | 70% | 80% | 90% |
|---|---|---|---|---|---|---|---|---|---|
| 36°F98% of yrs | Nov 22 | Nov 29 | Dec 2 | Dec 8 | Dec 14 | Dec 21 | Dec 27 | Jan 4 | Jan 21 |
| 32°F54% of yrs | Dec 8 | Dec 18 | Dec 26 | Dec 31 | Jan 4 | Jan 16 | Jan 31 | Feb 12 | Feb 27 |
| 28°F7% of yrs | too rare for a date | ||||||||
Freeze probabilities 1991–2020 at Pismo Beach, CA, from NOAA NCEI U.S. Climate Normals. Where a temperature is reached in fewer than 99.5% of years, the dates describe only the years that reach it. Not a forecast.
Frost risk on any date in 93420 →Compare Arroyo Grande with another place →
Weather by month in Arroyo Grande
August is the warmest month at Pismo Beach, CA, averaging 71°F by day and 55°F at night; December is the coldest at 65°F and 44°F. From March to November the chance of a 32°F night stays under 10% each month. In spring, February still brings one in 19% of years.
Warmth for growing adds up to 3,364 growing degree days a year (base 50°F), fewer than at 75% of the 283 California stations. 43% of them (1,438) have built up by the end of June, and August adds the most, 406. Precipitation totals 18.0 inches a year, most in February (4.0") and least in July (0.0"); May to September bring 4% of it.
| Month | High °F | Low °F | Precip. in | 32°F night | Nights ≤ 32°F | GDD 50°F |
|---|---|---|---|---|---|---|
| Jan | 65 | 44 | 3.5 | 22% | 1 | 147 |
| Feb | 65 | 44 | 4.0 | 19% | <1 | 136 |
| Mar | 68 | 46 | 3.0 | 8% | <1 | 218 |
| Apr | 70 | 48 | 1.0 | 3% | <1 | 270 |
| May | 72 | 50 | 0.5 | 0% | 0 | 338 |
| Jun | 71 | 51 | 0.2 | 0% | 0 | 328 |
| Jul | 70 | 54 | 0.0 | 0% | 0 | 375 |
| Aug | 71 | 55 | 0.0 | 0% | 0 | 406 |
| Sep | 72 | 54 | 0.1 | 0% | 0 | 383 |
| Oct | 73 | 53 | 0.8 | 0% | 0 | 389 |
| Nov | 69 | 46 | 1.8 | 2% | 0 | 233 |
| Dec | 65 | 44 | 3.1 | 21% | <1 | 141 |
Monthly normals 1991–2020 at Pismo Beach, CA (39 ft), NOAA NCEI. "32°F night": chance of at least one in the month. GDD: growing degree days, base 50°F.
Compared with the next station
The nearest other station, San Luis Obispo Airport, CA, 10 miles northwest of Arroyo Grande and 161 feet higher, has a last frost 1 day earlier (January 31), a first frost 24 days earlier (December 11), a season 43 days shorter.
When it snows in Arroyo Grande, California
Measurable snow is rare here: only 0 of 19 winters from 1991 to 2020 recorded 0.1 inch or more at San Luis Obispo Poly, CA, 14.3 miles away, so there is no typical first-snow date to plan around.
Where these figures come from
ZIP 93420 is 8 miles from Pismo Beach, CA, which stands at 39 feet, the nearest NOAA station that publishes freeze probabilities for 1991–2020. 3 other ZIP codes share the station. The 2023 USDA Plant Hardiness Zone Map lists ZIP 93420 in zone 9b, the band where the coldest night of the year averaged 25 to 30°F (-3.9 to -1.1°C) over 1991–2020; a zone describes winter lows, not frost dates.
Frost dates across California →
Hardiness zone and temperature range: USDA Plant Hardiness Zone Map 2023 (USDA-ARS, Oregon State University), ZIP-code listing, unchanged. °C converted from °F by this site.
Thirty-year averages, not a forecast: check the forecast before planting out. How stations are matched and which pages are offered to search engines: methodology.