National Weather Service Forecast for: Saint Helena CA
Issued by: National Weather Service San Francisco Bay Area/Monterey, CA
Updated: 1:26 am PDT Aug 20, 2026
 
Overnight

Overnight: Patchy fog. Otherwise, mostly cloudy, with a low around 55. Calm wind.
Patchy Fog

 Thursday

Thursday: Areas of fog before 9am. Otherwise, partly sunny, with a high near 88. Light south southeast wind.
Areas Fog
then Partly
Sunny
 Thursday
Night
Thursday Night: Patchy fog after 3am. Otherwise, mostly cloudy, with a low around 55. Calm wind.
Mostly Cloudy
then Patchy
Fog
 Friday

Friday: Patchy fog before 8am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 87. Calm wind becoming west southwest around 5 mph in the afternoon.
Patchy Fog
then Mostly
Sunny
 Friday
Night
Friday Night: Patchy fog after 1am. Otherwise, partly cloudy, with a low around 53. West southwest wind around 5 mph becoming calm in the evening.
Mostly Clear
then Patchy
Fog
 Saturday

Saturday: Areas of fog before 9am. Otherwise, sunny, with a high near 88.
Areas Fog
then Sunny
 Saturday
Night
Saturday Night: Patchy fog after 4am. Otherwise, partly cloudy, with a low around 54.
Mostly Clear
then Patchy
Fog
 Sunday

Sunday: Patchy fog before 8am. Otherwise, mostly sunny, with a high near 89.
Patchy Fog
then Sunny
 Sunday
Night
Sunday Night: Patchy fog after 3am. Otherwise, partly cloudy, with a low around 54.
Partly Cloudy
then Patchy
Fog
Lo 55 °F Hi 88 °F Lo 55 °F Hi 87 °F Lo 53 °F Hi 88 °F Lo 54 °F Hi 89 °F Lo 54 °F

 

Overnight
 
 Patchy fog. Otherwise, mostly cloudy, with a low around 55. Calm wind.
Thursday
 
 Areas of fog before 9am. Otherwise, partly sunny, with a high near 88. Light south southeast wind.
Thursday Night
 
 Patchy fog after 3am. Otherwise, mostly cloudy, with a low around 55. Calm wind.
Friday
 
 Patchy fog before 8am. Otherwise, cloudy, then gradually becoming mostly sunny, with a high near 87. Calm wind becoming west southwest around 5 mph in the afternoon.
Friday Night
 
 Patchy fog after 1am. Otherwise, partly cloudy, with a low around 53. West southwest wind around 5 mph becoming calm in the evening.
Saturday
 
 Areas of fog before 9am. Otherwise, sunny, with a high near 88.
Saturday Night
 
 Patchy fog after 4am. Otherwise, partly cloudy, with a low around 54.
Sunday
 
 Patchy fog before 8am. Otherwise, mostly sunny, with a high near 89.
Sunday Night
 
 Patchy fog after 3am. Otherwise, partly cloudy, with a low around 54.
Monday
 
 Areas of fog before 9am. Otherwise, mostly sunny, with a high near 86.
Monday Night
 
 Areas of fog. Otherwise, partly cloudy, with a low around 53.
Tuesday
 
 Areas of fog. Otherwise, mostly sunny, with a high near 87.
Tuesday Night
 
 Patchy fog. Otherwise, partly cloudy, with a low around 54.
Wednesday
 
 Areas of fog. Otherwise, mostly sunny, with a high near 88.

 

Forecast from NOAA-NWS for Saint Helena CA.