Boise ID Average Temperatures by Month

The numbers here tell you how hot and cold the weather usually is in Boise, Idaho during each month of the year.

The average high and low temperatures are listed below monthly and annually for the city, in both degrees Fahrenheit and Celsius.

Maximums and minimums are only part of the temperature picture. To fill in the rest, there's information on how many days a month get above or below a given temperature.

To find out how often it rises over 70, 80 or 90 °F each month in Boise, scroll down farther. There are also monthly and yearly counts of days with cold weather.

The first set of high and low temperatures are averages for 2010 to 2019. Everything else here is based on 1991 to 2020 weather.

10-year temperature averages for Boise, 2010 to 2019
High °F	Low °F		High °C	Low °C
38	24	January	4	-4
46	30	February	8	-1
56	36	March	13	2
63	40	April	17	4
72	47	May	22	8
82	55	June	28	13
94	63	July	34	17
92	62	August	33	17
80	54	September	27	12
65	42	October	18	6
50	32	November	10	0
38	25	December	4	-4
65	43	Year	18	6

30-year temperature averages for Boise, 1991 to 2020
High °F	Low °F		High °C	Low °C
39	26	January	4	-4
46	29	February	8	-2
56	35	March	13	2
62	40	April	17	4
72	48	May	22	9
81	54	June	27	12
93	62	July	34	17
91	61	August	33	16
80	53	September	27	11
65	42	October	18	5
49	32	November	9	0
39	25	December	4	-4
64	42	Year	18	6

Days of Hot Weather in Boise

About half of summer days at Boise see the temperature climb into the 90s Fahrenheit. The 90-degree weather can show up here as early as April and last until October. Highs in the 100s occur during June, July and August, amounting to six days a year on average.

Number of days in Boise of at least 70, 80 or 90 °F
	70 °F 21 °C	80 °F 27 °C	90 °F 32 °C
January	0	0	0
February	0	0	0
March	2	0	0
April	7	1	0
May	18	8	1
June	26	17	7
July	31	29	22
August	31	29	20
September	25	16	5
October	9	3	0
November	0	0	0
December	0	0	0
Year	149	103	55

How Often Boise Has Cold Temperatures

Freezing temperatures can happen in Boise anytime from September until May. Boise typically has 108 frosty nights a year. The coldest nights drop down to below 0 °F (-18 °C). It normally only gets that cold here one or two times a year, usually in December and January.

On an average of 16 days annually the thermometer never rises above freezing. Days that chilly show up during November to March.

Days per month on average in Boise when the minimum temperature drops to 32, 20 or 10 °F or below
	10 °F -12 °C	20 °F -8 °C	32 °F 0 °C
January	2	8	26
February	0	3	20
March	0	0	11
April	0	0	5
May	0	0	1
June	0	0	0
July	0	0	0
August	0	0	0
September	0	0	0
October	0	0	4
November	1	3	16
December	1	9	25
Year	4	23	108

Boise Temperatures: Averages by Month

Days of Hot Weather in Boise

How Often Boise Has Cold Temperatures

References

More on Weather in Idaho