As Glen correctly pointed out, this is a big topic and a lot of variables come into play. Your actual seeing can be influenced by very local factors such as neighbouring properties (house next door has a hot roof, for example) or local geographical features (hills which influence airflow, lakes and other bodies of water).
I usually check
SkippySky to get an approximate idea of what local weather-based seeing conditions will be like and would recommend that others do the same. Anything more specific than that requires measurement from your actual location.