It all depends on what you want to do! The summer is hard to beat. With the sun being up and shining around 18-24 hours a day in the summer months, it is always a good time coming up between June-August. That is when you'll enjoy temperatures of around 55F- 80F. The weather up here is very sporadic so you'll probably enjoy everything from sunshine to storms in a few days alone. We have world renown train tours that can take you to a good amount of the state and provide you with virtually limitless options for activities, whether you are looking for something to fill your day or want to go on a multi-day backpacking trip. It is also a good place to not plan anything specific and just let your whims take you! Come up and get lost for a bit, I highly recommend it.