NY to Arches National Park - further questions

I like to use the NOAA (US Weather Service) 7 day forecast

7day for Moab

It has a map that you can zoom and select a specific location. It then gives an altitude adjusted forecast.

For example for Moab (4000') it predicts 82/55 today and tonight. For La Sal Mtns at 11,500 ft a short distance to the east 51/42.

Also look at their hourly forecast graph:
http://forecast.weather.gov/MapClick.php?lat=38.57608&lon=-109.5501708984375&unit=0&lg=english&FcstType=graphical

For a regional view, try their graphical forecast
http://graphical.weather.gov/sectors/centrockies.php?element=MaxT