Safety trumps "the show must go on". If you are uncomfortable driving or with the weather in general, DO NOT GO.
Rehearsals are cancelled if the forecast for the time when you would be driving is -30F or lower. If the forecast calls for rain and the streets are icy, DO NOT GO. We simply cannot walk or drive on that stuff.
There is always a chance of rain for outdoor concerts. We do not play if it is raining, but summer weather can be very spotty around here. All too often, concerts have been cancelled early. Then the rain stops, the sun comes out, and an audience appears, seemingly from nowhere, and we are embarrassed. Nobody likes that.
The current strategy is that a concert is not cancelled until concert time arrives, or even a few minutes after. If it is still raining, and fish are beginning to swim around on stage, the director (only!) can cancel the event. If we come prepared for the perfect storm, Murphy says it won't rain.
C'mon, folks. This IS Alaska.