St. Helena, California

Last updated: 4:32 PM CDT  ·  Refresh
21°C
Feels like 19°
Clear
▲ 22°  /  ▼ 7°
Wind
2 mph WNW
Humidity
31%
Dew Point
3°
Pressure
29.32 inHg
Visibility
10 mi
UV Index
6.7
Cloud Cover
3%
Sunrise
7:31 AM
Sunset
6:14 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: St. Helena is currently clear at 21°C. Dry conditions are expected through the next 24 hours. Sunrise: 7:31AM · Sunset: 6:14PM.

Alerts

No active alerts for this location.
31 AQI · Good Dominant: O3 Air Quality
Hourly Forecast · Next 24 Hours
Now
21°
3%
3 PM
22°
8%
4 PM
22°
8%
5 PM
21°
8%
6 PM
18°
8%
7 PM
16°
8%
8 PM
15°
8%
9 PM
13°
8%
10 PM
12°
3%
11 PM
12°
3%
12 AM
12°
3%
1 AM
11°
3%
2 AM
11°
3%
3 AM
11°
3%
4 AM
11°
3%
5 AM
8°
3%
6 AM
8°
3%
7 AM
8°
3%
8 AM
8°
3%
9 AM
13°
3%
10 AM
14°
3%
11 AM
15°
3%
12 PM
16°
3%
1 PM
17°
3%
7-Day Forecast
Today
22° 7°
Mostly Clear.
Thu
19° 8°
Overcast.
Fri
18° 6°
Haze.
Sat
17° 6°
Mostly Cloudy.
Sun
21° 6°
Clear.
Mon
22° 9°
Clear with a 25% chance of rain.
Tue
22° 10°
Clear with a 35% chance of rain.
TimeTempConditionsPrecipWindHumidity
Now 21° Clear 3% 2 mph WNW 31%
3 PM 22° Mostly Clear 8% 2 mph W 28%
4 PM 22° Partly Cloudy 8% 2 mph W 31%
5 PM 21° Mostly Cloudy 8% 2 mph WSW 36%
6 PM 18° Mostly Cloudy 8% 2 mph WSW 43%
7 PM 16° Mostly Cloudy 8% 2 mph W 49%
8 PM 15° Mostly Cloudy 8% 2 mph WNW 53%
9 PM 13° Mostly Cloudy 8% 2 mph NNW 55%
10 PM 12° Mostly Cloudy 3% 2 mph NNW 57%
11 PM 12° Mostly Cloudy 3% 2 mph NNW 58%
12 AM 12° Overcast 3% 2 mph NNW 57%
1 AM 11° Overcast 3% 2 mph N 56%
2 AM 11° Overcast 3% 2 mph N 55%
3 AM 11° Overcast 3% 2 mph N 55%
4 AM 11° Overcast 3% 2 mph NNE 56%
5 AM 8° Overcast 3% 2 mph NE 56%
6 AM 8° Overcast 3% 2 mph NE 56%
7 AM 8° Overcast 3% 2 mph NE 56%
8 AM 8° Overcast 3% 2 mph ENE 54%
9 AM 13° Overcast 3% 2 mph ESE 48%
10 AM 14° Overcast 3% 2 mph SE 44%
11 AM 15° Overcast 3% 2 mph SE 40%
12 PM 16° Overcast 3% 3 mph SSE 38%
1 PM 17° Overcast 3% 3 mph SSE 36%
15-Day Forecast
Today
10/28
Mostly Clear
8%
7°
22°
Thu
10/29
Overcast
3%
8°
19°
Fri
10/30
Haze
3%
6°
18°
Sat
10/31
Mostly Cloudy
16%
6°
17°
Sun
11/1
Clear
3%
6°
21°
Mon
11/2
Clear
25%
9°
22°
Tue
11/3
Clear
35%
10°
22°
Wed
11/4
Clear
25%
9°
21°
Thu
11/5
Clear
3%
9°
22°
Fri
11/6
Drizzle
60%
9°
22°
Sat
11/7
Clear
42%
9°
21°
Sun
11/8
Drizzle
60%
10°
22°
Mon
11/9
Drizzle
60%
11°
22°
Tue
11/10
Drizzle
60%
10°
21°
Wed
11/11
Drizzle
60%
10°
20°
31
Good
U.S. Air Quality Index · Dominant: O3
50 100 150 200

Air quality is satisfactory and poses little or no health risk.

Pollutant Breakdown · Today
PM2.5
Fine particulate matter
24 AQI 4.5 µg/m³
O3
Ground-level ozone
Dominant
31 AQI 34 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Thu 31 Good 31 24
Fri 32 Good 32 22
Sat 34 Good 34 32
About the Air Quality Index
0–50 Good
51–100 Moderate
101–150 Unhealthy for Sensitive Groups
151–200 Unhealthy
201–300 Very Unhealthy
301–500 Hazardous

The U.S. AQI runs 0–500. The overall value equals the highest individual pollutant sub-index, and the dominant pollutant is the one driving it. PM2.5 (fine particles) is reported in µg/m³ and ozone (O3) in ppb. Forecast source: NWS NAQFC.

1000850700500400300250200150100 -40-30-20-10010203040 0.41247101624 LCLLFCEL0°C Temperature (°C) Pressure (hPa)
Temp Dewpoint Parcel (SB) CAPE CIN Dry adiabat Moist adiabat Mixing ratio
RAP
Valid Wed Oct 28, 20:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 50 60 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE67 J/kg
MLCAPE10 J/kg
MUCAPE67 J/kg
SBCIN0 J/kg
MLCIN-3 J/kg
Lifted Index7.1
Kinematics
0–6 km Shear17 kt
0–1 km Shear4 kt
Eff. Shear—
0–1 km SRH-5
0–3 km SRH6
Eff. SRH—
Storm Motion9° @ 21 kt
0–1 km EHI-0.0
Composite Parameters
Sig. Tornado0.0
STP (eff)—
Supercell—
K-Index-12.4
Thermo & Levels
PWAT0.33 in
0–3 km LR6.4 °C/km
700–500 LR7.0 °C/km
Total Totals34.4
LCL760 hPa
LFC993 hPa
EL838 hPa
Freezing Lvl10,997 ft