The snow is melting so slowly this year that skiing has been extended all over the Western United States. Such events do happen, but not very often. Of course the predictions over the past 10 years make it seem that such late skiing would never happen again, but of course those predictions are being proven wrong again.
Here is a list of ski locations that are open and some history of such events that I have been able to find.
Aspen, Colorado – Closed in April, but re-opening for the long weekend and plans to stay open on future weekends for as long as the snow holds out. There is 70 inches of snow at the base and that has been stable since April. This is the third time that extra skiing has happened at Aspen in the past 20 years. 1995 and 2008 being the other two. The latest skiing that has ever happened at Aspen was July 4th.
Mammoth Mountain – They are scheduled to the 4th of July and have had 3 inches of new snow in the last 24 hours.
Arapahoe Basin – Is 2/3 open at the end of May. 91 inches of snow at the base and there is fresh snow in the past 3 days.
Snowbird – Has 6 inches of new snow in the last 48 hours and is open. Conditions look pretty good there.
The Ski Channel has an updated list on the other resorts still open.
I bet that website is happy that ski conditions are still good as June has arrived.