temperature in terryville.
- The highest monthly average temperature in Terryville for July is 73 degrees. The lowest monthly average temperature in Terryville for January is 29 degrees. The most monthly precipitation in Terryville occurs in October with 7.5 inches. The air quality index in Terryville is 21% better than the national average. The pollution index in Terryville is 184% worse than the national average.