Earliest and Latest Days of 100° F in Boise

This is a list of the earliest and latest days in the year with a high temperature of at least 100 °F in Boise, Idaho history. It is based on NOAA data from the years 1911–2024.

Also see:

Earliest 100 degree day in Boise?

The earliest in the year that Boise, Idaho had a high temperature of at least 100 °F is May 28 which happened in 1919.

Latest 100 degree day in Boise?

The latest in the year that Boise, Idaho had a high temperature of at least 100 °F is September 14 which happened in 2000.

Earliest Days ≥ 100 °F

Date	Year	Temperature
May 28	1919	101 °F
June 3	2021	103 °F
June 6	1977	101 °F
June 8	2016	101 °F
June 10	1930	100 °F
June 12	1940	102 °F
June 12	1918	100 °F
June 13	1918	100 °F
June 14	1987	101 °F
June 14	1974	105 °F
June 15	1999	100 °F
June 16	1988	102 °F
June 16	1974	104 °F
June 17	1974	105 °F
June 17	1961	104 °F
June 18	2003	101 °F
June 18	1974	103 °F
June 18	1961	100 °F
June 18	1940	100 °F
June 19	1988	103 °F
June 19	1974	103 °F
June 19	1940	109 °F
June 19	1925	100 °F

Latest Days ≥ 100 °F

Date	Year	Temperature
September 14	2000	101 °F
September 7	2022	104 °F
September 7	1924	101 °F
September 6	2022	101 °F
September 5	2020	100 °F
September 5	1963	100 °F
September 4	2020	102 °F
September 4	1931	100 °F
September 4	1924	105 °F
September 3	2022	102 °F
September 3	2007	101 °F
September 3	1998	100 °F
September 3	1931	100 °F
September 2	2022	101 °F
September 2	1950	101 °F
September 1	1987	101 °F
September 1	1976	100 °F
September 1	1945	102 °F
August 31	2022	106 °F
August 31	2004	102 °F