I also used the weather.gov site:
https://forecast.weather.gov/MapCli...rine=0&unit=0&lg=en#.XxyKjZ5KjIUand the various model runs at:
https://weather.us/model-charts/standard and:
https://weather.us/model-charts/euroYou want to check the trend and consistency. If all of those sites forecast clear skies and 0% chance of precipitation for the day of your hike and the day before and after, you're good and can safely summit at any time of the day. If the forecasts conflict, consider an early start and turn around when you see clouds start to build. A few small isolated clouds can turn into rain and thunder in 2 hours or less.
FWIW, on my July 20 summit, Mountain Forecast predicted clear skies in the AM, some clouds in the PM, and calm winds. The actual weather was clear skies from 6-9 AM, cloudy by noon, light rain showers and some thunder in the afternoon (not intense or very near), breezy conditions from 4 - 5 PM, and clear skies and calm winds after 6 PM.
Also, Mountain Forecast usually underestimates high temps and overestimates low temps. The diurnal temperature variation is typically greater than what Mountain Forecast predicts.