Here's the link:
https://forecast.weather.gov/MapClick.p ... u1xhGhKjccFor the most accurate spot forecast, enlarge the map and drag your cursor to the closest location to your route then left click. You'll be able to see the overall forecast with temperature and specific conditions for area and elevation.
As a general rule, afternoons and eastern areas are more prone to rain and thunderstorms during the summer months. If "weather"/thunderstorms are forecast, plan your travel time to avoid exposed areas and high passes accordingly. Also, figure on temperature differentials to be 2-3 degrees lower per 1000 ft of elevation gain.