Best time to travel to Alaska

Might want to do the Banff Jasper portions at the end of the trip instead of the first, might work out better weatherwise, busy wise in Banff Jasper, etc. Anyway you will have a great trip enjoy yourself.

September has always been our favorite time to travel in Yukon and Alaska. Yup, some of the tourist services and commercial campgrounds close first week of September, but we enjoy camping in the Yukon gov't campgrounds so no problem :B

keep the rain, other wise the mosquitoes will eat you alive

Mosquitoes in Alaska don't care if it's raining or not.

AK is a LONG drive. Your biggest expense is fuel. Chase the snow north and let it chase you south. Stay as long as you can.

our cousins used to tell me they loved it when we came to visit. they noted that it stopped raining when we showed up. and started backup when we left. keep the rain, other wise the mosquitoes will eat you alive

One thing about it...you will miss the crowds and have your pick of campgrounds. You could get a little dusting in late September up around Denali, but it usually melts off during the day. I travel through there every September pulling a 24' boat to the Yukon river and never had a bad trip. Bring bug dope, late Aug and early Sept no seeums can be bad.

Many touristic things were closing down, or thinking about closing down, around the start of September last year at the tail end of my Alaska trip. Steward and Prince George might be nigh to ghost towns in your itinerary. Fairbanks wouldn't be so much (though e.g. the Pioneer Park attractions would be closing around that time) since it's very much a year-round city, not as completely dependent on tourism for its continued existence. Gas and services along the way would likely also be less available, but should still be entirely adequate. Weather certainly could be a consideration towards the end of the timeframe, too, as was mentioned.

I think it would be preferable to shift your schedule a few weeks back if practical, but if not I'm sure it would be a delightful trip none the less.

Most of our friends have been a mid May departure ambling up through Alberta/BC returning mid to late August early September being in BC area typically as berry season starts, going up one and back the other Highways Hwy 37 and Hwy 97 (Cassier/Stewart/Alcan). Both highways have a lot to offer for stop offs.

Canada is absolutely breath taking, so you'll likely want to allow yourselves plenty of time travelling through BC and Alberta enroute.

Just saying and to each their own.

Most folks seem to head north by mid June returning mid August.

Mother Nature is the big factor!
You could have into the first of October for decent weather. It will or could get cold. Snow and rain is possible.
You may want to visit the southern portion on the way backrather than northbound.