(CBS SF) -- The sunniest day of the year happens to fall on Father's Day 2015, as the summer solstice occurs Sunday, June 21st, marking the astronomical and meteorological beginning of summer.
Now, "sunniest" means different things to different people. If you're stuck in the fog (San Francisco expects partly cloudy skies Friday), you may not be able to appreciate it much, but the hemisphere will. The Northern Hemisphere has its longest day of the year, setting into motion the warming pattern that gives July its heat. The Bay Area, of course, is cooled by the 50-60 degree temperatures of the Pacific, and doesn't develop its hottest month until September.
Various cultures from Swedish, Norse, Finnish, French, Spanish, Pagan, ancient British, and to even Catholics celebrating St. John the Baptist's day all mark the solstice in various ways, but key to many is appreciating the sun as its final direct rays blink out at the horizon around 8:30 p.m.
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Sunday will bring 14 hours, 44 minutes of daylight, with the sun rising over San Jose at 5:47 a.m. and not setting until 8:31 p.m. It won't get completely dark until 10:25 p.m. Sunday, according to Farmer's Almanac.
For San Francisco, it's almost 4 minutes more of daylight, with the sun setting at 8:35 p.m. Dawn begins around 3:52 a.m. Sunday. That's a lot of daylight.
It will only be truly dark for about 5 and a half hours when you factor in twilight at dusk and dawn.
While we say longest "day" in regards to Sunday, the 24-hour period known as a day won't be any longer.
The longest actual "day" or 24-hour period of the year will actually be June 30th, during the leap second. A full second has to be added to clocks to keep everything (atomic clocks, etc.) in synch with earth's slowing rotation. That's truly the longest "day" for a while.
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