During the summer, the weather is typically anticyclonic due to the presence of the North Pacific anticyclone, with resultant clear skies and large diurnal temperature ranges.
Marine fossils indicate that the terranes were probably a group of islands originating out in the South Pacific hundreds of million years ago.
A drive through the residential parts of town display many glacier erratic's that originated 20 miles away up the Icicle valley near Mt. About 19,000 years ago a large rock slide dammed the Columbia River near Rock Island (just south of Wenatchee).
The temporary dam, in conjunction with one of the Lake Missoula floods, caused the water to flow back up the Wenatchee valley where it was stopped by the glacier at Leavenworth.
The terranes landed on North America about 90mya(million years ago) in the middle of the Cretaceous period.
As they smashed into their new home they were a puzzle of north- south slices.