May or September to visit Yellowstone/Grand Tetons?
 

Just starting to plan a trip West for 2012, but not sure if we should do May or September? We are a couple and want to stay in the Parks if we can still make reservations. Which time of the year would be least crowded with decent weather? Any help or suggestions welcomed! Thanks.

Mom, we went to Yellowstone over Memorial weekend and the first week of June, 2011. We encountered snow avalanches, rock slides, road closures because of snow, and lots of trails closed because of snow/erosion and bear activity. It is the moutains, so anything goes as far as weather.
The next time I go it will be later in the year, like August/September. Even though May is shoulder season, I thought there was lots of people and traffic, but I live in a rural area of the world.
We stayed at the Old Faithful Inn, I highly recommend it for its history and awesomeness, but you need reservations early. Enjoy your trip ziggypop

We were there the first few days of September. The weather was great, cold mornings but midday temps around 70. It didn't seem too crowded either.

We were there in late June and did see a little snow, but the roads were passable that year. The nice thing about that time of year was the baby elk, bison, etc. were in abundance. You could also get snow in September, but the elk would be in rut which would be interesting to see.

I would guess that September would have better weather, unless there happened to be a year with an early spring.

May is probably too early to get to most of the features in Yellowstone -- even if all the roads are open (no guarantee that they will be), the trails will most definitely be covered in snow. Some events are still unavailable till late JUNE, if you can believe that.

http://www.nps.gov/yell/planyourvisi...closedates.htm

We just returned from a Sept 10-20 trip and had fine weather, frosty mornings and warm afternoons with a few cloudy/rainy spells. No road closures, but a few facilities were shutting for the winter already.

I love O.F. Inn for the history and charm, but must warn that is is really challenging for the mobility impaired -- dark corridors, stairs inconveniently located, hard-to-find elevators, standard rooms very cramped. Do stay there if you are ablebodied or can at least reserve a spacious room, though! Nothing beats the view of the geysers (Beehive as well as OF) from the Inn's porch.

We've been really lucky with good weather in early June in Yellowstone but I wouldn't chance going in May if I had a tight schedule. Weather is just to unpredictable that early in the season. September has been a great time weather wise and that's when we like to go.

Utahtea

September is usually going to be better for weather.

We have been during both May and September more than once and would definitely choose September if you have never been and have the choice of which time to come.

Mid-May most facilities are still not open, and as has been said you will chance snow in many locations. You would still be able to see all the major geysers and thermal features along with the buffalo and elk. You might be able to see some babies. Crowds are less, but that is why most facilities aren't open.

After Labor day again some of the facilities close but you won't be worried about snow affecting what you see. I think there is more bear activity as they are getting ready for hibernation. The Elk are gathering for rut and that is one of my favorite times to see them. The weather is usually mild. It will still be crowded, but not like the summer months.

As a former Montana resident and frequent visitor to YNP I'd go for September. The weather in May is a little more iffy and some of the roads may not be open.
Sept. is usually sunny days, cold nights and a lot less people on the roads. You'll still see a lot of people in early Sept, but nothing like July or August.

You already have plenty of feedback on this, but I'll pile on a vote for September. You can expect elk bugling, some fall golds (later in the month perhaps), good weather, and no crowds.

We'd like to go in the spring some time to see the baby critters, but "spring" there would be no sooner than June.

THANK YOU..THANK YOU... for all the information! I love using Fodors, as I always get great responses from other travelers!! We probably will be going in September!! Thanks, again.

I'll post a trip report soon. We just came back from a trip the first week of Oct. We encountered a few weather-related issues, but nothing to quibble about from our perspective. We heard the elk bugle, enjoyed the fabulous golden aspens and animals from elk to moose to coyote and bald eagles. A definite vote for Sept. from me. It was truly the trip of a lifetime. We can't wait to go back. Again, trip report within a week, I hope. Maybe it will help you! I, too, found Fodors incredibly helpful and will return the favor asap.

I still owe a trip report. Life became a bit chaotic upon our return, but will try to post highlights within the month. I truly appreciate everyone's reports and want to return the favor.