Amateur astronomers are also weather-watchers, paying close attention to daytime cloud patterns and TV weather maps. They soon learn that a summer sky filled with puffy cumulus clouds during the day often heralds a clear night sky.
If the sky is clear, the Milky Way may be seen even from suburban locations, and you are more likely to find faint objects such as nebulas.
Moisture of any kind in A the air degrades the transparency of the sky. Clear nights usually come after a cold front sweeps out haze and humidity, then brings a dry high-pressure center (marked with an H on weather maps). Nights with a low dewpoint also tend to be transparent. The dewpoint is the temperature at which moisture in the air condenses, and a low dewpoint means moisture is unlikely to condense out of the atmosphere as the temperature falls during the night.