June 21 is the longest day of the year, with 19 hours of daylight in Anchorage, 22 in Fairbanks, and 18 in Southeast. But from early May through September, days are considerably longer than at lower latitudes.
Alaska's sky is light nearly all night long from late May to late July (unless you're out and about at 3am). And it's light past 10pm for another month on either side of that.
You'll find Alaska's summer temperatures surprisingly pleasant. Daytime highs range from 60F - 80F. Nighttime lows are refreshingly cool, dipping into the 40's - 50's. May and September are 5 - 10 cooler.
