With the National parks being so popular this time of year, and many of them only having a short season to repair the roads, you can always visit the NPS website and find the park[s] you are visiting for up to date info on conditions.
This summer there is quite a big construction program in Yellowstone.
Expect delays on the Mount Carmel highway between Zion and Bryce with day time closures and long diversions.
The Wawona Rd  to the Southern entrance of Yosemite has delays of up to 30 -60 mins.
In the Grand Tetons there are a few projects and you can expect up to 30 min delays on Teton park Rd near to Jenny lake.
Large vehicle [RV] alert. The Generals highway in Seqouia NP has expected delays of up to 1 hour and a new 22ft lenght restriction for the time being !!
Trail ridge Rd in RMNP is being worked on and could have combined delays along it's lenght of up to 1 hour.
Keep up to date with the goings on at the Grand canyon.
All links will update automatically so info may differ to that I posted today.
Anyone who has recently visited a park and can report any updates, please do !