St. Helena, California

Last updated: 1:26 PM CDT  ·  Refresh
25°C
Feels like 22°
Clear
▲ 29°  /  ▼ 11°
Wind
6 mph NNE
Humidity
28%
Dew Point
5°
Pressure
29.28 inHg
Visibility
10 mi
UV Index
9.2
Cloud Cover
1%
Sunrise
5:47 AM
Sunset
8:38 PM
Drag to pan · double-click to forecast a point
WeatherAI™ Analysis

WeatherAI Analysis: St. Helena is currently clear at 25°C. Dry conditions are expected through the next 24 hours. Sunrise: 5:47AM · Sunset: 8:38PM.

Alerts

No active alerts for this location.
27 AQI · Good Dominant: O3 Air Quality
Hourly Forecast · Next 24 Hours
Now
25°
3%
12 PM
24°
3%
1 PM
28°
3%
2 PM
29°
3%
3 PM
28°
3%
4 PM
27°
3%
5 PM
29°
3%
6 PM
29°
3%
7 PM
27°
3%
8 PM
25°
3%
9 PM
22°
3%
10 PM
21°
3%
11 PM
19°
3%
12 AM
18°
3%
1 AM
16°
3%
2 AM
15°
3%
3 AM
14°
3%
4 AM
14°
3%
5 AM
11°
3%
6 AM
13°
3%
7 AM
14°
3%
8 AM
15°
3%
9 AM
18°
3%
10 AM
19°
3%
7-Day Forecast
Today
29° 11°
Clear.
Mon
29° 11°
Mostly Clear.
Tue
27° 11°
Clear.
Wed
28° 9°
Clear.
Thu
28° 9°
Clear.
Fri
31° 9°
Clear.
Sat
32° 11°
Clear.
TimeTempConditionsPrecipWindHumidity
Now 25° Clear 3% 6 mph NNE 28%
12 PM 24° Clear 3% 5 mph N 23%
1 PM 28° Clear 3% 4 mph N 22%
2 PM 29° Clear 3% 4 mph WNW 24%
3 PM 28° Clear 3% 8 mph W 26%
4 PM 27° Clear 3% 10 mph W 28%
5 PM 29° Clear 3% 11 mph W 30%
6 PM 29° Clear 3% 10 mph W 34%
7 PM 27° Clear 3% 9 mph WNW 38%
8 PM 25° Clear 3% 8 mph WNW 43%
9 PM 22° Clear 3% 6 mph WNW 50%
10 PM 21° Clear 3% 4 mph WNW 57%
11 PM 19° Clear 3% 3 mph WNW 61%
12 AM 18° Clear 3% 3 mph WNW 63%
1 AM 16° Clear 3% 3 mph WNW 66%
2 AM 15° Clear 3% 2 mph NW 67%
3 AM 14° Clear 3% 2 mph NNW 68%
4 AM 14° Mostly Clear 3% 2 mph N 68%
5 AM 11° Mostly Clear 3% 2 mph NNE 68%
6 AM 13° Mostly Clear 3% 2 mph NE 63%
7 AM 14° Mostly Clear 3% 2 mph ENE 59%
8 AM 15° Mostly Clear 3% 3 mph ENE 54%
9 AM 18° Clear 3% 3 mph ENE 48%
10 AM 19° Clear 3% 4 mph NE 42%
15-Day Forecast
Today
6/28
Clear
3%
11°
29°
Mon
6/29
Mostly Clear
3%
11°
29°
Tue
6/30
Clear
3%
11°
27°
Wed
7/1
Clear
3%
9°
28°
Thu
7/2
Clear
3%
9°
28°
Fri
7/3
Clear
3%
9°
31°
Sat
7/4
Clear
3%
11°
32°
Sun
7/5
Clear
3%
11°
31°
Mon
7/6
Clear
3%
11°
31°
Tue
7/7
Clear
3%
11°
34°
Wed
7/8
Clear
3%
13°
33°
Thu
7/9
Clear
3%
13°
35°
Fri
7/10
Clear
3%
13°
35°
Sat
7/11
Clear
3%
13°
36°
Sun
7/12
Clear
3%
13°
35°
27
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
12 AQI 2.2 µg/m³
O3
Ground-level ozone
Dominant
27 AQI 29 ppb
3-Day Outlook
DayAQICategoryO₃PM2.5
Mon 27 Good 27 12
Tue 24 Good 24 16
Wed 31 Good 31 26
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 Sun Jun 28, 17:00'Z' · F0 · 130 (13 km CONUS/NA)
Hodograph · kt
10 20 30 40 50 60 70 80 SM
0–1 1–3 3–6 6–9 km
Instability
SBCAPE93 J/kg
MLCAPE11 J/kg
MUCAPE93 J/kg
SBCIN0 J/kg
MLCIN0 J/kg
Lifted Index8.4
Kinematics
0–6 km Shear66 kt
0–1 km Shear6 kt
Eff. Shear—
0–1 km SRH-35
0–3 km SRH-82
Eff. SRH—
Storm Motion307° @ 28 kt
0–1 km EHI-0.0
Composite Parameters
Sig. Tornado-0.0
STP (eff)—
Supercell—
K-Index-2.9
Thermo & Levels
PWAT0.50 in
0–3 km LR7.8 °C/km
700–500 LR4.8 °C/km
Total Totals31.4
LCL744 hPa
LFC991 hPa
EL788 hPa
Freezing Lvl10,709 ft