October 2023 Summary – Seventh Warmest on Record
Blue Hill Observatory October 2023 Summary:
October 2023 was much warmer and drier than average. The approximated 24-hour mean temperature for the month of 56.2 deg F was 4.9 degrees warmer than the 1891-2020 130-year average for October, and it was 4.0 degrees warmer than the 1991-2020 30-year average. The month was the seventh warmest October on record. The average maximum temperature of 65.5 deg F was 4.5 degrees warmer than the 30-year normal, and it tied as the sixth warmest on record. The average minimum temperature of 49.4 deg F tied as the third warmest on record for October, and it was 5.4 degrees warmer than the 30-year normal. The highest temperature was 81F on the 3rd and 4th. The lowest temperature was 35F on the 31st, which was the first temperature below 40F of the season and the latest date ever observed for a temperature below 40F. The monthly minimum temperature of 35F tied as the fifth warmest with five other years. Another warm day occurred on the 28th with a high temperature of 80F, which was one of the latest readings this warm ever observed so late in the season. Total precipitation was 1.97 inches, which was 3.52 inches less than the 30-year normal, reversing the generally wet pattern during the summer months. The greatest amount in 24 hours was 0.76 inches during the passage of a strong coastal storm on the 21st, during which a minimum sea-level pressure of 29.09 inches, the lowest for the month, was observed. There were no thunderstorm days during October. The average water vapor pressure, which is an absolute measure of water vapor in the air, was the fifth highest on record for October at 12.1 mb. The mean wind speed was only 9.6 mph, which was by far the lowest on record for the month, and the prevailing wind direction was from the southwest. The highest wind gust was 40 mph from the northwest during the rain storm on the 21st. October bright sunshine was close to average with 186.0 hours, or 56 percent of possible, which was one percent more than the long-term average for the month.
BHO Highest October Approximated 24-Hour Mean Temperature, deg F (1885-2023):
1) 59.2 in 2017
2) 58.4 in 1947
3) 56.9 in 2007
4) 56.6 in 1971
5) 56.5 in 1963
6) 56.3 in 2021
7) 56.2 in 2023
8) 55.7 in 1946
BHO Highest October Average Maximum Temperature, deg F (1885-2023):
1) 70.1 in 1947
2) 68.5 in 1963
3) 68.0 in 2017
4) 66.4 in 1946
5) 66.1 in 2007
6) 65.5 in 1931
65.5 in 2023
8) 65.4 in 1971
BHO Highest October Average Minimum Temperature, deg F (1885-2023):
1) 51.7 in 2017
2) 49.5 in 2007
3) 49.4 in 2021
49.4 in 2023
5) 49.2 in 1971
6) 49.1 in 1947
7) 48.2 in 1913
BHO Latest Maximum Temperature 80 deg F and Above (1885-2023):
1) 81 on 2 November 1950
2) 81 on 28 October 1919
80 on 28 October 2023
4) 80 on 27 October 1947
83 on 27 October 1963
6) 80 on 26 October 1963
7) 81 on 25 October 1963
BHO Latest First Minimum Temperature Below 40 deg F (1885-2023):
1) 31 October 2023 (35F)
2) 24 October 2013 (36F)
24 October 2021 (37F)
4) 22 October 1955 (34F)
5) 21 October 2005 (39F)
6) 20 October 1960 (38F)
7) 19 October 2014 (39F)
BHO Warmest October Monthly Minimum Temperature, deg F (1885-2023):
1) 37 in 2021
2) 36 in 1971
36 in 2004
36 in 2022
5) 35 in 1938
35 in 1994
35 in 1998
35 in 2017
35 in 2019
35 in 2023
BHO Highest October Average Water Vapor Pressure, mb (1932-2023):
1) 13.2 in 2017
2) 12.9 in 2021
3) 12.7 in 2007
4) 12.4 in 1971
5) 12.1 in 2023
6) 11.9 in 1990
11.9 in 2012
BHO Lowest October Average Wind Speed, mph (1885-2023):
1) 9.6 in 2023
2) 11.2 in 2013
11.2 in 2022
4) 11.3 in 2020
5) 11.4 in 2021
Mike Iacono
Chief Scientist
Blue Hill Observatory
