Weather in Tri-Cities in September
How warm is it in Tri-Cities in September?
In September the typical daytime high in Tri-Cities is 24.2 °C on average, from 27.7 °C at the start to 21.2 °C at the end of the month.
That is 5.9 °C cooler than in August and 7.8 °C warmer than in October.
The last 10 years were 0.4 °C warmer than more than 40 years ago.
Click a day for more: afternoon and night, the usual range, records and how fast it is warming.
The average of the weather stations Spokane Intl Ap (199 km) and Payette (299 km); nearer ones count more.