Signal Hill, California Weather
Coastal fog thickens at dawn. Day 76 of spring. Read this microseason across nine climate regions →
Signal Hill weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 3Foggy——75°60°—
- ThursdayJun 4Foggy——71°58°-4°
- FridayJun 5Foggy——71°57°0°
- SaturdayJun 6Overcast——69°63°-2°
- SundayJun 7Mostly Clear——68°61°-1°
- MondayJun 8Overcast——70°62°+2°
- TuesdayJun 9Partly Cloudy——75°64°+5°
Ozone at AQI 103 — peak already passed at 1 PM under partly cloudy skies. AQI flat over the last 6 hours (within ±3 points). Levels should ease through evening.
CAUTION Sensitive groups (children, elderly, respiratory conditions) should limit prolonged outdoor exertion.
What's driving it
Ozone × UV × Sky
Ozone at AQI 103 — peak already passed at 1 PM under partly cloudy skies. Levels should ease through evening.
- Present
- AQI 103
- UV peak
- 6.5 at earlier today
- Sky at peak
- partly cloudy
- Projected peak
- AQI 103
PM × Wind × Precip
PM2.5 at 28.1 µg/m³, PM10 at 38.9 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.72
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- background
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
- 5:26 AM
- Moonset
- 3:16 PM
- In sign
- ♑︎ Capricorn
Coastal fog thickens at dawn
Signal Hill at a glance
- Today vs. normal: 8°F below the seasonal normal for this latitude
- Last frost: March 10 (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 | lettuce, peas, spinach, radishes | — |
| April | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | — |
| May | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | — | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | — | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | fall brassicas, garlic (overwinter), carrots | — |
| December | — | — |
A year in weather
Signal Hill's warmest month is August (~74°F mean) and its coldest is December (~57°F). Rainfall peaks in February (3.0 inches) and bottoms out in August (0.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 57° | 2.9″ | 4 |
| February | 58° | 3.0″ | 5 |
| March | 60° | 1.6″ | 3 |
| April | 63° | 0.6″ | 1 |
| May | 66° | 0.3″ | 1 |
| June | 69° | 0.1″ | 0 |
| July | 73° | 0.1″ | 0 |
| August | 74° | 0.0″ | 0 |
| September | 73° | 0.1″ | 0 |
| October | 68° | 0.5″ | 1 |
| November | 62° | 0.8″ | 2 |
| December | 57° | 2.1″ | 3 |
Regional context
Signal Hill 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 Signal Hill?
- Signal Hill's last spring frost typically falls around mid-March, and the first fall frost arrives around mid-December.
- What is the rainy season in Signal Hill?
- February is the wettest month with about 3.0 inches of rain on average; the city receives roughly 12 inches annually.
- What is the warmest month in Signal Hill?
- August is typically warmest, averaging about 74°F.
- What is the coldest month in Signal Hill?
- December is typically coldest, averaging about 57°F.
- When can I start a vegetable garden in Signal Hill?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-March); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Signal Hill get?
- Signal Hill averages about 20 rainy days per year.
- What hardiness zone is Signal Hill?
- Signal Hill'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
Signal Hill, California sits in a hot-summer Mediterranean climate zone. January means hover near 57°F while July averages 73°F — a 16°F seasonal swing.
Across the year, Signal Hill receives about 12 inches of precipitation spread over roughly 20 rainy days.
The rhythm of the year is set by latitude (33.8°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.