Yellowstone Last wk in May or 1st wk in June

I'm still following, thanks to all that has responded

We have gone up to Grand Teton and Yellowstone toward the end of May and early June and the folks on here are correct, the weather is a little "iffy" a lot of times. One year at Grand Teton over Memorial Day we lost three days of fishing due to a lot of rain, another time we took grandsons up for a week early in June and had snow in both Grand Teton and Yellowstone, but not enough that we couldn't sightsee and fish. One other time wife and I just took our boat up for the weekend and stayed at Jackson Lake Lodge, woke up Memorial Day morning with six inches of very wet snow on the boat cover. So, you just have to take your chances and be prepared for any weather, it's in Wyoming where if you don't like the weather, just wait a while, it will change.

We were in GTNP the second week of June and then onto Yellowstone NP the third week of June. No big crowds, weather was very nice. Stay at Grizzly RV Park in the town of West Yellowstone, very nice and all the avaliable services the town has to offer.

We arrived June 12th this past summer. Not one hint that winter had happened. Nice jacket weather except for the warmest few hours of the day. We really enjoyed the weather.

From what I understand from Rangers, only east coast schools are out by then. Seemed like he said there would be a large crowd coming the week after we left. Our crowds were tolerable.

We got there on June 9th, "08 it snowed that night at Madison, (lightly), it was right at 32 degrees for the first 2 nights, after that it started to warm up gradually.
You may want to check Campground opening dates, many are open in May, a few don't open till June. https://www.nps.gov/yell/planyourvisit/ocd_locale.htm
Madison is open year around,

Sounds like its a plan, thank you

First week of June will get same wx chances...visitation about the same. Big plus for that date is all visitor centers will be open and some Ranger programs will be up and running...not so before Memorial Day. Best time of the year...oops don't let that out. :) :)

I was there in 2008. May 15 at Grand Tetons GV campground first day it open. 1,000's of elk going to high ground. Snow on the ground but roads open. The next week at YS had one day that snow closed one road until noon when the snow melted. Saw a Grizzle Bear kill a buffalo calf near Old Faithful.

Late May is one of the best time to see GT and YS because of the snow makes the area look better. Very few people but lots of wild life.

You can also get snow in June or July.

as late as you can can do it is my two cents. we were there in very early june a few years ago and it was open to Madison and down to Old Faithful, but snow showers were blowing across the norther half of the park.
it IS a good time to go to avoid the crowds and also to maybe see some of the spring babies.

I lived in the area for 5 years, one year we didn't get a light snow in late May or early June.
At the same time it had been in the upper 70's just before.

I really like that time of year, much of the game is still down in the valleys and basins, plus there are few "Turons".

The Madison area is usually open by then.