Diamond Bar, California Weather
Coastal fog thickens at dawn. Day 77 of spring. Read this microseason across nine climate regions →
Diamond Bar weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Foggy——84°56°—
- FridayJun 5Foggy——80°58°-4°
- SaturdayJun 6Foggy——80°58°0°
- SundayJun 7Clear——80°60°0°
- MondayJun 8Clear——82°61°+2°
- TuesdayJun 9Clear——83°64°+1°
- WednesdayJun 10Overcast——80°63°-3°
PM2.5 at 22.5 µg/m³, PM10 at 31.9 µg/m³ — typical background levels with no transport signature. 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 41 now. With UV 8.8 peaking around 1 PM under clear skies, surface ozone likely climbs to AQI 48 by mid-afternoon.
- Present
- AQI 41
- UV peak
- 8.8 at 1 PM
- Sky at peak
- clear
- Projected peak
- AQI 48
PM × Wind × Precip
PM2.5 at 22.5 µg/m³, PM10 at 31.9 µg/m³ — typical background levels with no transport signature.
- PM2.5/PM10
- 0.71
- 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).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 6:05 AM
- Moonset
- 4:14 PM
- In sign
- ♒︎ Aquarius
Coastal fog thickens at dawn
Diamond Bar at a glance
- Today vs. normal: 12°F below the seasonal normal for this latitude
- Last frost: March 11 (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 4, 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.