Weather in Mexico's Riviera Nayarit. One of the chief considerations in planning a vacation is the weather, and it is the weather that makes Riviera Nayarit an excellent choice for anyone trying to escape the cold of a northern winter, or the heat of a southern summer.
Asotin County Weather. The average temperature of Asotin County is 49.59Â°F, which is about the same as the Washington average temperature of 50.47Â°F and is lower than the national average temperature of 54.45Â°F. Historical Weather. Heating Cost Index, #24.
1 Average September temperature: 14.4ÂºC / 58ÂºF. 2  September average high: 18.3ÂºC / 65ÂºF. 3  September average low: 10ÂºC / 50ÂºF. 4  September is not so rainy in a city famous for its rain. 5  Expect rain about 7 - 9 days out of 30 in September.