Byron, CA Weather & Growing Conditions
Local forecast, frost dates, hardiness zone and planting guidance for Byron, a community in Contra Costa County, California.
Today
103°F
Sunny
Sunny, with a high near 103. West northwest wind 5 to 10 mph, with gusts as high as 18 mph.
7-day forecast for Byron
| When | Temp | Forecast | Wind | Precip |
|---|---|---|---|---|
| Today | 103°F | Sunny | 5 to 10 mph WNW | 0% |
| Tonight | 63°F | Clear | 2 to 9 mph W | 0% |
| Wednesday | 101°F | Sunny | 2 to 9 mph WNW | 0% |
| Wednesday Night | 63°F | Clear | 2 to 9 mph W | 0% |
| Thursday | 100°F | Sunny | 2 to 10 mph W | 0% |
| Thursday Night | 65°F | Clear | 2 to 10 mph W | 0% |
| Friday | 104°F | Sunny | 2 to 10 mph WNW | 0% |
| Friday Night | 67°F | Clear | 3 to 10 mph W | 0% |
| Saturday | 104°F | Sunny | 3 to 10 mph W | 0% |
| Saturday Night | 68°F | Clear | 3 to 10 mph WSW | 0% |
| Sunday | 99°F | Sunny | 5 to 12 mph W | 0% |
| Sunday Night | 64°F | Clear | 7 to 12 mph WSW | 0% |
| Monday | 94°F | Sunny | 5 to 12 mph W | 0% |
| Monday Night | 61°F | Mostly Clear | 3 to 12 mph W | 0% |
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 Aug 4, 2026.