Hourly Weather | Tomorrow Wednesday, March 18, 2026
Active Weather Warnings
Fullerton, California
12 AM
Night
64°
Feels Like 64°
0
Humidity: 58%
UV Index: 0
Wind: 4 mph
1 AM
Night
64°
Feels Like 64°
0
Humidity: 61%
UV Index: 0
Wind: 4 mph
2 AM
Cloudy Night
63°
Feels Like 63°
0
Humidity: 64%
UV Index: 0
Wind: 4 mph
3 AM
Night
61°
Feels Like 61°
0
Humidity: 66%
UV Index: 0
Wind: 4 mph
4 AM
Night
61°
Feels Like 61°
0
Humidity: 67%
UV Index: 0
Wind: 4 mph
5 AM
Night
61°
Feels Like 61°
0
Humidity: 68%
UV Index: 0
Wind: 2 mph
6 AM
Night
57°
Feels Like 57°
0
Humidity: 72%
UV Index: 0
Wind: 4 mph
7 AM
Sunny Weather
59°
Feels Like 59°
0
Humidity: 64%
UV Index: 0
Wind: 4 mph
8 AM
Sunny Weather
55°
Feels Like 57°
0
Humidity: 79%
UV Index: 1
Wind: 4 mph
9 AM
Sunny Weather
64°
Feels Like 68°
0
Humidity: 60%
UV Index: 2
Wind: 5 mph
10 AM
Sunny Weather
73°
Feels Like 77°
0
Humidity: 44%
UV Index: 3
Wind: 5 mph
11 AM
Sunny Weather
81°
Feels Like 86°
0
Humidity: 34%
UV Index: 4
Wind: 5 mph
12 PM
Sunny Weather
88°
Feels Like 91°
0
Humidity: 28%
UV Index: 6
Wind: 6 mph
1 PM
Sunny Weather
91°
Feels Like 95°
0
Humidity: 24%
UV Index: 6
Wind: 7 mph
2 PM
Sunny Weather
95°
Feels Like 99°
0
Humidity: 22%
UV Index: 6
Wind: 8 mph
3 PM
Sunny Weather
99°
Feels Like 100°
0
Humidity: 20%
UV Index: 4
Wind: 8 mph
4 PM
Sunny Weather
97°
Feels Like 97°
0
Humidity: 21%
UV Index: 3
Wind: 8 mph
5 PM
Sunny Weather
93°
Feels Like 93°
0
Humidity: 24%
UV Index: 2
Wind: 8 mph
6 PM
Sunny Weather
91°
Feels Like 90°
0
Humidity: 27%
UV Index: 1
Wind: 7 mph
7 PM
Sunny Weather
88°
Feels Like 84°
0
Humidity: 32%
UV Index: 0
Wind: 6 mph
8 PM
Night
82°
Feels Like 81°
0
Humidity: 37%
UV Index: 0
Wind: 6 mph
9 PM
Night
77°
Feels Like 75°
0
Humidity: 47%
UV Index: 0
Wind: 5 mph
10 PM
Night
73°
Feels Like 72°
0
Humidity: 54%
UV Index: 0
Wind: 5 mph
11 PM
Night
70°
Feels Like 68°
0
Humidity: 55%
UV Index: 0
Wind: 5 mph

Weather Alerts and Warnings for Fullerton

Severe Future Likely

Extreme Heat Watch

Extreme Heat Watch issued March 14 at 5:51AM PDT until March 20 at 8:00PM PDT by NWS San Diego CA
Mar 16, 10:00 AM Mar 20, 8:00 PM
WHAT: Dangerously hot conditions with temperatures 85 to 90 near
the coast, up to 105 inland.

WHERE: Orange County Coastal Areas, Orange County Inland Areas,
San Bernardino and Riverside County Valleys-The Inland Empire, San
Diego County Coastal Areas, San Diego County Valleys, and Santa
Ana Mountains and Foothills.

WHEN: From Monday morning through Friday evening.

IMPACTS: Heat related illnesses increase significantly during
extreme heat events.

ADDITIONAL DETAILS: High temperatures next week will be 20 to
potentially 30 degrees above
normal for this time of year, where record breaking heat is likely.
+ Read More
Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes.
Updated: Mar 14, 10:45 AM Source: NWS Alert
Moderate Expected Likely

Heat Advisory

Heat Advisory issued March 17 at 12:33AM PDT until March 20 at 8:00PM PDT by NWS San Diego CA
Mar 17, 12:33 AM Mar 20, 8:00 PM
WHAT: High temperatures in the upper 80s to mid 90s expected.

WHERE: Orange County Inland Areas.

WHEN: Until 8 PM PDT Friday.

IMPACTS: Hot temperatures may cause heat illnesses.
+ Read More
Drink plenty of fluids, stay in an air-conditioned room, stay out of the sun, and check up on relatives and neighbors. Do not leave young children and pets in unattended vehicles. Car interiors will reach lethal temperatures in a matter of minutes. Take extra precautions when outside. Wear lightweight and loose fitting clothing. Try to limit strenuous activities to early morning or evening. Take action when you see symptoms of heat exhaustion and heat stroke.
Updated: Mar 17, 2:40 AM Source: NWS Alert