Frost dates / California / Modesto
Frost dates in Modesto, CA
The station on this page is MODESTO CITY CO AP, CA US (USW00023258), 3 miles from the city point. Population in the Census 2024 estimate is 220,592.
Zone 9bUSDA average annual extreme minimum 25°F to 30°F, from ZIP 95351 (1 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 31 | Earlier date. A last 32°F on or after this day is common. |
| 50% | January 31 | Median. |
| 10% | February 25 | 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 20 | Earlier date. A first 32°F on or before this day is uncommon. |
| 50% | December 5 | Median. |
| 90% | January 6 | 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% | 343 |
| 50% | 312 |
| 90% | 279 |
28°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | February 6 | January 8 | December 16 |
| First, on or before | December 1 | December 21 | January 20 |
| Season at least | 365 days | 352 days | 321 days |
36°F threshold
| 10% | 50% | 90% | |
|---|---|---|---|
| Last, on or after | March 31 | March 1 | February 3 |
| First, on or before | November 8 | November 22 | December 9 |
| Season at least | 294 days | 262 days | 231 days |
Station MODESTO CITY CO AP, CA US (USW00023258). Completeness flag R, 20 years used for the 32°F dates. NCEI’s annual probability of at least one day at or below 32°F is 97.1%. Freeze dates are conditional on that threshold occurring. Elevation 22.3 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 Modesto · Zone 9b
Check a crop against this station
Modesto, CA
Zone 9bAverage annual extreme minimum 25°F to 30°F
Outside the median season Growing seasonTicks: 10%, 50%, and 90%
California. Nearest qualified station: MODESTO CITY CO AP, CA US (USW00023258), 3 miles. Median last 32°F January 31. Median first 32°F December 5. The 50% growing-season length is 312 days.
Open the ZIP page · Crop guides for California
32°F probabilities at this station
| 10% | 50% | 90% | |
|---|---|---|---|
| Last 32°F on or after | February 25 | January 31 | December 31 |
| First 32°F on or before | November 20 | December 5 | January 6 |
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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