(NEW YORK) -- Thursday marks the first day of summer and the longest day of the year across much of the Northern Hemisphere.
New York City will experience 15 hours and 6 minutes of daylight, while Los Angeles will see 14 hours and 26 minutes of daylight. In Fairbanks, Alaska, residents will experience a whopping 21 hours and 48 minutes of daylight.
But the first day of summer has also brought some extreme weather across the country.
Flooding from Pennsylvania to Texas
Major flash flooding hit western Pennsylvania Wednesday afternoon and evening.
Nearly 3 inches of rain were reported in just two hours in the Pittsburgh area, flooding roadways and leaving people stranded. Several people had to be rescued from their cars.
Pittsburgh has had nearly 150 percent of its average yearly rainfall so far, and 2018 is far from over.
In south Texas, flash flooding has swamped neighborhoods and covered roadways. Some areas saw nearly 15 inches of rain in just 72 hours.
More heavy rain has been falling Thursday morning, and flash flood watches remain in effect.
Three to 4 inches of rain are possible in south Texas. But relief is on the way -- much of Texas will be dry on Friday and Saturday.
Dangerous heat is building in the Southwest.
Temperatures are set to reach or exceed 110 degrees in Palm Springs, Las Vegas and Phoenix on Thursday. The heat will last several days and will reach Northern and Central California on Friday and Saturday.
Temperatures in Sacramento Valley are set to rise above 100 degrees both days.
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