Byron, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Byron, a community in Contra Costa County, California.
This Afternoon
69°F
Sunny
Sunny. High near 69, with temperatures falling to around 66 in the afternoon. Northwest wind 5 to 8 mph.
7-day forecast for Byron
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| This Afternoon | 69°F | Sunny | 5 to 8 mph NW | 1% |
| Tonight | 49°F | Partly Cloudy | 3 mph W | 1% |
| Thursday | 72°F | Sunny | 2 to 7 mph WNW | 0% |
| Thursday Night | 49°F | Mostly Clear | 2 mph W | 0% |
| Friday | 72°F | Sunny | 1 to 5 mph NW | 0% |
| Friday Night | 48°F | Clear | 2 mph NNW | 0% |
| Saturday | 74°F | Sunny | 2 mph NE | 0% |
| Saturday Night | 50°F | Mostly Clear | 0 mph | 0% |
| Sunday | 74°F | Sunny | 0 to 3 mph NW | 0% |
| Sunday Night | 51°F | Partly Cloudy | 2 mph N | 0% |
| Monday | 73°F | Mostly Sunny | 0 to 3 mph NW | 0% |
| Monday Night | 50°F | Partly Cloudy | 2 mph WNW | 1% |
| Tuesday | 73°F | Sunny | 2 mph NW | 1% |
| Tuesday Night | 51°F | Mostly Clear | 1 mph NW | 4% |
Forecast source: National Weather Service (api.weather.gov) for Byron (37.876, -121.642). Updated through the day.
Growing snapshot for Byron
Last spring frost
Jan 19
First fall frost
Dec 10
Growing season
330 days
Hardiness zone
9b
More local growing data for Byron: nearby ZIP 94505 weather · frost dates · planting calendar · California frost dates
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Climate data from the nearest NOAA station, Tracy Pumping Plt, Ca (5.3 mi from Byron). Frost dates are 1991–2020 averages, not a forecast. Page updated Nov 4, 2026.