Average September Temperatures for Idaho

Average temperatures for September at cities, towns, parks and lakes throughout Idaho are listed below in degrees Fahrenheit and Celsius.

You can jump to a separate table for each region of the state: Eastern, Central, Southwestern and Northern Idaho.

The tables give the normals for maximum and minimum temperatures based on weather data collected from 1991 to 2020 by the US National Centers for Environmental Information.

Eastern Idaho

Average September temperatures
High °F	Low °F	Place	High °C	Low °C
73	38	Driggs	23	3
75	41	Idaho Falls	24	5
68	32	Island Park	20	0
78	41	Malad City	26	5
78	49	Pocatello	26	9
77	43	Preston	25	6
73	41	Saint Anthony	23	5

Central Idaho

Average daily temperatures in September
High °F	Low °F	Place	High °C	Low °C
69	38	Craters of the Moon Monument	21	4
69	36	Ketchum	21	2
78	44	Lake Walcott, Minidoka Dam	26	7
76	39	Middle Fork Lodge	24	4
74	41	Salmon	24	5
75	44	St. Maries	24	7
70	25	Stanley, Sawtooth Recreation Area	21	-4
76	45	Twin Falls	24	7

Southwestern Idaho

September temperatures: daily averages
High °F	Low °F	Place	High °C	Low °C
80	53	Boise	27	11
83	55	Brownlee Reservoir Dam	28	13
84	49	Bruneau	29	9
77	36	Idaho City	25	2
80	49	Lake Lowell, Deer Flat Dam	27	9
72	36	McCall	22	2
82	48	Mountain Home	28	9

Northern Idaho

Average September temperatures
High °F	Low °F	Place	High °C	Low °C
73	45	Bonners Ferry	23	7
74	48	Coeur d’Alene	23	9
74	32	Elk City	23	0
73	41	Kellogg	23	5
80	52	Lewiston	26	11
76	40	Moscow	25	4
71	42	Mullan	22	5
74	42	Porthill	23	6
71	37	Powell	21	3
80	45	Riggins	26	7
72	42	Sandpoint	22	6
71	44	Wallace	22	7

Average Temperatures for Idaho in September

Eastern Idaho

Central Idaho

Southwestern Idaho

Northern Idaho

Reference

More Idaho Weather Information