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Blue Hill Observatory October 2024 Summary:
October temperature was above average with much less rainfall and much more sunshine than expected. The approximated 24-hour mean temperature for the month of 54.3 deg F was 3.0 degrees warmer than the 1891-2020 130-year average for October, and it was 2.1 degrees warmer than the 1991-2020 30-year average. The average maximum temperature of 64.7 deg F was 3.7 degrees warmer than the 30-year normal, and the average minimum temperature of 45.6 deg F was 1.6 degrees warmer than the 30-year normal. October temperature started close to average, then turned cooler during the middle of the month and ended with many warm days during the last two weeks. The highest temperature for October reached 82F on the 21st, which was a new record for the date surpassing 79F set in 1979. The lowest temperature was 35F on the 15th and 17th. The mean water vapor pressure, which is an absolute measure of water vapor in the air, was 10.1 mb, which corresponds to a mean dew point of 50F and was average for the month. The total precipitation was 0.76 inches, which was 4.73 inches less than the 30-year normal. This amount was the sixth lowest total precipitation on record for October, and it continued a period of four consecutive months drier than average. The September-October two-month total rainfall of 2.59 inches was the third lowest on record, and the July-October four-month rainfall total of 8.12 inches was less than half the expected rainfall for this period and it was the seventh lowest on record for July to October. As of early November, this deficit has left parts of eastern Massachusetts in a severe drought. The greatest amount in 24 hours during October was just 0.27 inches on the 7th. There were only five days with measurable precipitation in October, which was one of the lowest on record. There were no thunderstorm days during October. The mean wind speed was 10.9 mph, which was the second lowest on record for the month, and the prevailing wind direction was from the west-northwest. The highest wind gust was 44 mph from the northwest on the 12th. In the very dry pattern, October sunshine was well above average with 237.2 hours of bright sunshine, or 72 percent of possible, which was the third highest on record for October and seventeen percent more than the long-term average for the month.
BHO Warmest October Monthly Minimum Temperature, deg F (1885-2024):
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
35 in 2024
BHO Lowest October Precipitation, inches (1885-2024):
1) 0.22 in 1924
2) 0.39 in 1994
3) 0.50 in 1946
4) 0.61 in 1935
5) 0.63 in 1897
6) 0.76 in 2024
7) 0.79 in 2001
8) 1.09 in 2013
BHO Lowest September-October Precipitation, inches (1885-2024):
1) 2.48 in 1914
2) 2.50 in 1941
3) 2.59 in 2024
4) 2.81 in 1897
5) 2.81 in 1952
6) 3.04 in 1921
7) 3.23 in 1912
BHO Lowest July-October Precipitation, inches (1885-2024):
1) 6.46 in 1957
2) 7.39 in 1910
3) 7.48 in 1997
4) 7.53 in 1968
5) 7.77 in 1965
6) 7.78 in 1941
7) 8.12 in 2024
8) 8.13 in 1929
BHO Lowest October Number of Days Measurable Precipitation (1885-2024):
1) 3 in 1897
3 in 1924
3 in 1947
4) 4 in 1963
5) 5 in 1914
5 in 1929
5 in 1966
5 in 1971
5 in 2024
BHO Lowest October Average Wind Speed, mph (1885-2024):
1) 9.6 in 2023
2) 10.9 in 2024
3) 11.2 in 2013
11.2 in 2022
5) 11.3 in 2020
6) 11.4 in 2021
BHO Highest October Bright Sunshine, hours (1886-2024):
1) 251.5 in 1963 [76%]
2) 238.7 in 1924 [72%]
3) 237.2 in 2024 [72%]
4) 231.3 in 1956 [70%]
5) 229.5 in 1974 [69%]
228.7 in 1935 [69%]
Mike Iacono
Chief Scientist
Blue Hill Observatory
