Thorndale is located in western Chester county in the Chester Valley about 40 miles west of downtown Philadelphia. The general topography of the area is rolling hills. The Thorndale weather station lies 335 feet above sea level. The North Valley Hills rise to over 700 feet above sea level a mile north of Thorndale while the South Valley Hills peak at near 600 feet ASL about a half mile south of Thorndale. However, due to its position 40 miles inland to the west of Philadelphia many winter storms that mix with or turn to rain in Philadelphia will remain snow in the higher elevations of Chester County.
Summers are warm and rather humid.
Usually highs reach into the mid-80s with nighttime lows near 60 . However, summer nights in the 50's are to be expected several times each month of the summer season. The occasional maritime influence tends to produce a fairly uniform weather pattern, resulting in occasional prolonged Hot, Hazy and Humid periods. During the period June-August, daytime highs exceed 90 on the average of 21 days with nighttime lows rarely lower than 45 . The record high was 107 set back on August 7, 1918.