Bethel Island, California Weather
Coastal fog thickens at dawn. Day 78 of spring. Read this microseason across nine climate regions →
Bethel Island weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Clear——89°58°—
- FridayJun 5Clear——91°62°+2°
- SaturdayJun 6Overcast——85°50°-6°
- SundayJun 7Overcast——85°48°0°
- MondayJun 8Light Rain16%0.18″65°49°-20°
- TuesdayJun 9Light Drizzle15%—78°57°+13°
- WednesdayJun 10Clear——94°56°+16°
Ozone at AQI 66 — peak already passed at 1 PM under clear skies. AQI up 21 in the last 6 hours — air quality is degrading. Levels should ease through evening.
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 66 — peak already passed at 1 PM under clear skies. Levels should ease through evening.
- Present
- AQI 66
- UV peak
- 1.0 at earlier today
- Sky at peak
- clear
- Projected peak
- AQI 66
PM × Wind × Precip
PM2.5/PM10 ratio 0.49 with 14 mph wind — characteristic of long-range haze transport rather than a local source.
- PM2.5/PM10
- 0.49
- 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
- 7:04 AM
- Moonset
- 5:23 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
Bethel Island at a glance
- Today vs. normal: 6°F above the seasonal normal for this latitude
- Last frost: April 4 (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 5, 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
Bethel Island's warmest month is July (~76°F mean) and its coldest is January (~48°F). Rainfall peaks in January (2.7 inches) and bottoms out in July (0.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 48° | 2.7″ | 6 |
| February | 52° | 2.4″ | 6 |
| March | 57° | 1.9″ | 5 |
| April | 61° | 0.9″ | 2 |
| May | 67° | 0.4″ | 1 |
| June | 73° | 0.1″ | 0 |
| July | 76° | 0.0″ | 0 |
| August | 75° | 0.0″ | 0 |
| September | 73° | 0.1″ | 0 |
| October | 66° | 0.4″ | 1 |
| November | 55° | 1.2″ | 3 |
| December | 48° | 2.5″ | 6 |
Frequently asked
- When does it freeze in Bethel Island?
- Bethel Island's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Bethel Island?
- January is the wettest month with about 2.7 inches of rain on average; the city receives roughly 13 inches annually.
- What is the warmest month in Bethel Island?
- July is typically warmest, averaging about 76°F.
- What is the coldest month in Bethel Island?
- January is typically coldest, averaging about 48°F.
- When can I start a vegetable garden in Bethel Island?
- 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 Bethel Island get?
- Bethel Island averages about 30 rainy days per year.
- What hardiness zone is Bethel Island?
- Bethel Island'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
Bethel Island, California sits in a hot-summer Mediterranean climate zone. January means hover near 48°F while July averages 76°F — a 28°F seasonal swing.
Across the year, Bethel Island receives about 13 inches of precipitation spread over roughly 30 rainy days.
The rhythm of the year is set by latitude (38.0°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.