The Winter Solstice occurs at 9:30 p.m. Pacific time Wednesday night when the Earth's axial tilt from the sun is at its maximum of 23 degrees, 26 seconds.  

On the Winter Solstice, the North Pole has its farthest tilt away from the sun, as does the entire Northern Hemisphere.

Wednesday night is the longest night of the year.

Seattle is technically in night for 15 hours, 34 minutes and 37 seconds.

Since this year's solstice occurs not too far before Midnight, Pacific time, it turns out Wednesday and Thursday will have the same length:

Eight hours, 25 minutes and 23 seconds.

Beginning Friday through the weekend, we start adding about five seconds to the length of the day, slowly accelerating thereafter.