Thunder, frequent lightning and local flash flooding are also expected, with large hail possible.
The watch is in effect for the entire region until 9 p.m. Wednesday, Aug. 7.
A half-inch of rainfall is possible during the afternoon and evening on Wednesday.
Look for storm activity to wrap up by around 11 p.m. Wednesday.
Thursday, Aug. 8 will be partly sunny with a high temperature in the mid 80s.
There's a 30-percent chance for more storms Thursday, mainly after 2 p.m., with the possibility for storms last through the evening.
The stormy stretch ends on Friday, Aug. 9, which will be sunny with a high temperature in the low 80s.
Check back to Daily Voice for updates.
Click here to follow Daily Voice New Canaan and receive free news updates.