Today is notable not only because a blizzard approaches, but because the sun sets earlier, at 1643 MST in Kalispell, than any other day of the year. The latest sunrise, at 0828 MST, occurs on New Year’s Day, and on a few days before and after. The shortest period of daylight, of course, occurs on the winter solstice, which occurs at 2359 UTC on 20 December this year. Those times assume a flat horizon, of course, so in Kalispell the the sun will set a few minutes earlier, and rise a few minutes later, than indicated in this table (PDF), which I created using the U.S. Naval Observatory’s Multiyear Interactive Computer Almanac, available from Willmann-Bell for $30. You can create your own table online at the USNO’s data services web page.