60°F
Clear Sky
St. Helena, Napa Valley
Updated 4:37 AM PT
Feels Like
56°F
Humidity
41%
Wind
3 mph NNE
Precipitation
None
Today's High
90°F
Today's Low
55°F
Sunrise
6:50 AM
Sunset
7:19 PM
Hourly Forecast
4 AM
60°
0%
5 AM
62°
0%
6 AM
61°
0%
7 AM
55°
0%
8 AM
56°
0%
9 AM
62°
0%
10 AM
72°
0%
11 AM
82°
0%
12 PM
86°
0%
1 PM
88°
0%
2 PM
89°
0%
3 PM
90°
0%
7-Day Forecast
Today
Overcast
90°
55°
💨 12 mph
Tomorrow
Foggy
83°
54°
💨 12 mph
Wed, Sep 16
Overcast
84°
52°
💨 11 mph
Thu, Sep 17
Overcast
83°
53°
💨 7 mph
Fri, Sep 18
Clear Sky
93°
58°
💨 9 mph
Sat, Sep 19
Clear Sky
97°
58°
💨 6 mph
Sun, Sep 20
Overcast
94°
58°
💨 6 mph
Napa Valley Weather Notes
St. Helena sits at the heart of the Napa Valley floor, sheltered by the Mayacamas Mountains to the west and the Vaca Range to the east. The valley's fog-channeling geography creates a natural air-conditioning effect — cool Pacific fog rolls in from San Pablo Bay each evening, burning off by mid-morning. Summer afternoons typically reach the 90s°F while winter lows can dip into the low 30s. The peak growing season runs May through October, and frost risk is highest December through February.