Earliest and Latest Days of 90° F in Boulder

This is a list of the earliest and latest days in the year with a high temperature of at least 90 °F in Boulder, Colorado history. It is based on NOAA data from the years 1893–2024.

Also see:

Earliest 90 degree day in Boulder?

The earliest in the year that Boulder, Colorado had a high temperature of at least 90 °F is March 17 which happened in 1910.

Latest 90 degree day in Boulder?

The latest in the year that Boulder, Colorado had a high temperature of at least 90 °F is October 5 which happened in 1947.

Earliest Days ≥ 90 °F

Date	Year	Temperature
March 17	1910	90 °F
May 15	1978	93 °F
May 16	1996	93 °F
May 17	1964	92 °F
May 18	1996	90 °F
May 19	2006	90 °F
May 20	2005	90 °F
May 20	1984	91 °F
May 20	1954	93 °F
May 21	2006	90 °F
May 23	2000	90 °F
May 23	1989	90 °F
May 23	1967	90 °F
May 24	1967	90 °F
May 26	1969	91 °F
May 26	1942	90 °F
May 27	2006	92 °F
May 27	1969	91 °F
May 28	2010	91 °F
May 28	2000	95 °F
May 28	1989	91 °F
May 28	1974	90 °F
May 28	1951	91 °F

Latest Days ≥ 90 °F

Date	Year	Temperature
October 5	1947	90 °F
October 1	1953	90 °F
September 30	1980	91 °F
September 28	2010	90 °F
September 27	2001	90 °F
September 27	1953	92 °F
September 27	1952	90 °F
September 26	2021	90 °F
September 24	1949	92 °F
September 23	1947	91 °F
September 22	1954	90 °F
September 22	1953	90 °F
September 20	2022	90 °F
September 20	2010	90 °F
September 20	1956	93 °F
September 20	1949	90 °F
September 19	2022	90 °F
September 19	2016	90 °F
September 19	2010	93 °F
September 19	1980	92 °F
September 19	1952	91 °F
September 19	1935	91 °F