Castroville, California Weather
Coastal fog thickens at dawn. Day 76 of spring. Read this microseason across nine climate regions →
Castroville weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Foggy——65°53°—
- ThursdayJun 4Overcast——65°51°0°
- FridayJun 5Clear——66°48°+1°
- SaturdayJun 6Overcast——63°52°-3°
- SundayJun 7Overcast——62°50°-1°
- MondayJun 8Overcast——64°50°+2°
- TuesdayJun 9Overcast——66°54°+2°
PM2.5/PM10 ratio 0.69 with 11 mph wind — characteristic of long-range haze transport rather than a local source. AQI flat over the last 6 hours (within ±3 points).
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 46 — peak already passed at 1 PM under overcast skies. Levels should ease through evening.
- Present
- AQI 46
- UV peak
- 7.1 at earlier today
- Sky at peak
- overcast
- Projected peak
- AQI 46
PM × Wind × Precip
PM2.5/PM10 ratio 0.69 with 11 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.69
- Wind
- breezy
- Recent rain
- 0h in last 6h
- Pattern
- transport
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
The higher the clouds, the finer the weather.
- Moonrise
- 5:51 AM
- Moonset
- 3:22 PM
- In sign
- ♑︎ Capricorn
Coastal fog thickens at dawn
Castroville at a glance
- Today vs. normal: 14°F below the seasonal normal for this latitude
- Last frost: March 28 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 3, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Castroville's warmest month is September (~64°F mean) and its coldest is December (~51°F). Rainfall peaks in January (2.6 inches) and bottoms out in July (0.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 52° | 2.6″ | 6 |
| February | 53° | 2.4″ | 6 |
| March | 55° | 2.1″ | 5 |
| April | 57° | 0.9″ | 3 |
| May | 59° | 0.4″ | 1 |
| June | 62° | 0.1″ | 0 |
| July | 63° | 0.0″ | 0 |
| August | 64° | 0.0″ | 0 |
| September | 64° | 0.1″ | 0 |
| October | 62° | 0.6″ | 1 |
| November | 56° | 1.3″ | 3 |
| December | 51° | 2.1″ | 5 |
Regional context
Castroville sits within a hot-summer Mediterranean climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Los Angeles, CA, San Francisco, CA, San Diego, CA, Riverside, CA, Sacramento, CA.
Frequently asked
- When does it freeze in Castroville?
- Castroville's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Castroville?
- January is the wettest month with about 2.6 inches of rain on average; the city receives roughly 13 inches annually.
- What is the warmest month in Castroville?
- September is typically warmest, averaging about 64°F.
- What is the coldest month in Castroville?
- December is typically coldest, averaging about 51°F.
- When can I start a vegetable garden in Castroville?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Castroville get?
- Castroville averages about 31 rainy days per year.
- What hardiness zone is Castroville?
- Castroville's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Castroville, California sits in a hot-summer Mediterranean climate zone. January means hover near 52°F while July averages 63°F — a 11°F seasonal swing.
Across the year, Castroville receives about 13 inches of precipitation spread over roughly 31 rainy days.
The rhythm of the year is set by latitude (36.8°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.