Bring your rain gear and cold weather clothing. Being from TX it will still feel like winter in the Yukon when you get there.
We left North Central WA in 2016 in Mid June and returned home mid Sept. Some snow in the northern Yukon on our way north and days of rain. Spent 3 nights in Fairbanks and it rained the entire time we were camped there.
Hwy 97 washed out back then South of Chetwyn BC so we diverted to the Casier Hwy to continue our way north.
When we crossed over the Top of the World Hwy to Dawson City Y.T. we slogged our way through 6" of mud on a section of the road due to the rain that had fallen there. I've drive the ToftWorld Hwy half a dozen times so I knew to expect the unexpected so I locked the trucks hubs in before we departed Chicken, AK. Never shifted the transfer case into 4x4 but it was close. Then we climbed into the clouds for around 50 miles and it was slitpea soup. 15-30 mph as visibility was near zero. Once we got closer to Dawson City we drooped down towards the Yukon River to take the ferry acroos to DC we also dropped out of the clouds and could see again.
Enjoy your trip north.