Earliest and Latest Days of 100° F in Boulder

This is a list of the earliest and latest days in the year with a high temperature of at least 100 °F in Boulder, Colorado history. It is based on NOAA data from the years 1893–2024.

Also see:

Earliest 100 degree day in Boulder?

The earliest in the year that Boulder, Colorado had a high temperature of at least 100 °F is June 12 which happened in 1952.

Latest 100 degree day in Boulder?

The latest in the year that Boulder, Colorado had a high temperature of at least 100 °F is September 2 which has happened twice, most recently in 2019.

Earliest Days ≥ 100 °F

Date	Year	Temperature
June 12	1952	100 °F
June 14	2006	100 °F
June 15	1952	100 °F
June 23	2012	102 °F
June 23	1954	104 °F
June 24	2012	101 °F
June 24	1954	100 °F
June 25	2012	101 °F
June 26	1994	101 °F
June 27	1990	100 °F
July 1	2012	100 °F
July 1	2002	101 °F
July 6	1973	100 °F
July 7	1989	100 °F
July 7	1951	100 °F
July 8	1989	100 °F
July 10	1954	100 °F
July 11	1954	104 °F
July 12	1971	100 °F
July 12	1954	103 °F

Latest Days ≥ 100 °F

Date	Year	Temperature
September 2	2019	100 °F
September 2	1983	100 °F
August 24	1936	102 °F
August 16	2002	100 °F
August 9	1947	101 °F
August 8	1969	101 °F
August 6	1979	101 °F
August 1	1938	100 °F
July 31	2002	100 °F
July 29	1980	100 °F
July 29	1947	100 °F
July 28	1947	100 °F
July 27	1947	101 °F
July 24	2003	101 °F
July 24	1953	101 °F
July 22	1931	102 °F
July 21	2005	101 °F
July 20	1998	100 °F
July 19	2022	100 °F
July 19	2017	100 °F
July 19	1934	100 °F