Frost dates / California / Simi Valley
Frost dates in Simi Valley, CA
The station on this page is WOODLAND HILLS PIERCE COLLEGE, CA US (USC00049785), 11.5 miles from the city point. Population in the Census 2024 estimate is 125,778.
Zone 10aUSDA average annual extreme minimum 30°F to 35°F, from ZIP 93065 (1.4 miles from the city point used on this page).
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
Last 32°F in spring
NCEI’s probability is the chance the last spring minimum of 32°F or lower occurs on or after the date.
| Probability | Date | How to read it |
|---|---|---|
| 90% | December 21 | Earlier date. A last 32°F on or after this day is common. |
| 50% | January 24 | Median. |
| 10% | March 5 | Later date. A last 32°F on or after this day is uncommon. |
First 32°F in fall
NCEI’s probability is the chance the first autumn minimum of 32°F or lower occurs on or before the date.
| Probability | Date | How to read it |
|---|---|---|
| 10% | November 27 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | December 15 | Median. |
| 90% | January 26 | Later date. A first 32°F on or before this day is common. |
32°F growing-season length
Days between the last spring 32°F and the first autumn 32°F. The figure is a length the season meets or exceeds at that probability, from NCEI, not a subtraction done on this site.
| Probability the season is at least this long | Days |
|---|---|
| 10% | 365 |
| 50% | 329 |
| 90% | 277 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | February 1 | December 31 | December 5 |
| First, on or before | December 1 | December 26 | January 25 |
| Season at least | 365 days | 365 days | 341 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | April 7 | March 2 | January 30 |
| First, on or before | November 12 | November 29 | December 19 |
| Season at least | 309 days | 271 days | 234 days |
Station WOODLAND HILLS PIERCE COLLEGE, CA US (USC00049785). Completeness flag R, 24 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 90.6%. Freeze dates are conditional on that threshold occurring. Elevation 240.8 m. The same probability language applies to the 28°F and 36°F rows when those dates passed the same quality checks.
Planting calendar for Simi Valley · Zone 10a
Check a crop against this station
Simi Valley, CA
Zone 10aAverage annual extreme minimum 30°F to 35°F
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
California. Nearest qualified station: WOODLAND HILLS PIERCE COLLEGE, CA US (USC00049785), 11.5 miles. Median last 32°F January 24. Median first 32°F December 15. The 50% growing-season length is 329 days.
Open the ZIP page · Crop guides for California
32°F probabilities at this station
| 10% | 50% | 90% | |
|---|---|---|---|
| Last 32°F on or after | March 5 | January 24 | December 21 |
| First 32°F on or before | November 27 | December 15 | January 26 |
Column order matches the NCEI file: for the last freeze, 10% is the later date and 90% is the earlier date. How to read the probabilities.
Planting calendar
Windows below are from UC ANR, UC Master Gardener Program, Time of planting, retrieved 2026-10-10. North and North Coast = Monterey County north; South Coast = San Luis Obispo County south; Interior Valleys = Sacramento, San Joaquin, and similar valleys; Desert Valleys = Imperial and Coachella Valleys. Source line on the page: California Master Gardener Handbook, Table 13.2, Adapted from Vegetable Gardening Illustrated 1994.
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