January 2023 Summary – Second Warmest and Lowest Sunshine on Record
Blue Hill Observatory January 2023 Summary:
January 2023 was exceptionally warm with more precipitation than expected and record low wind and sunshine. The approximated 24-hour mean temperature for the month of 35.0 deg F was 9.1 degrees warmer than the 1891-2020 130-year average for January, and it was 7.8 degrees warmer than the 1991-2020 30-year average. January 2023 tied with January 1932 as the second warmest on record behind only 35.6 deg F in January 1913. The average maximum temperature of 41.6 deg F was 6.9 degrees warmer than the 30-year normal, and it was the seventh warmest on record. The average minimum temperature of 29.1 deg F was 10.8 degrees warmer than the 30-year normal, and it was the warmest on record for January. The warmth persisted all the month, and 30 of the 31 days were warmer than normal. The warmest temperature was 55F on the 13th. The lowest temperature was 18F on the 11th, and this reading was the highest monthly minimum temperature ever observed in January. Water vapor pressure, which is an absolute measure of the amount of moisture in the air, averaged 6.0 mb during the month, which was a new record for January and much higher than the long-term mean of 3.7 mb. The total precipitation was 6.79 inches, which was 2.29 inches more than the 30-year normal. The greatest liquid equivalent precipitation in 24 hours, which was a combination of rain and melted snow, was 1.32 inches on the 22nd-23rd. Other storms brought 1.32 inches of rain and a couple of inches of melted snow on the 19th-21st and 1.30 inches of rain with traces of snow and sleet on the 25th-26th. There were 20 days with measurable precipitation during the month, which tied the record previously set in 1950, and this number was among the most recorded for any month of the year. In addition, there were twelve consecutive days with measurable precipitation from the 12th-23rd, which has never before occurred in January. Total snowfall for the month was 12.2 inches, which was 6.4 inches below normal. The greatest 24-hour snowfall was 4.1 inches on the 23rd. The mean wind speed was 11.4 mph, which was the lowest on record for January, and the prevailing wind direction was from the north, which was somewhat unusual for such a warm month. The highest wind gust was 54 mph from the south-southeast during the rainfall and warmth on the 13th. January bright sunshine was much below average with only 73.2 hours, or 26 percent of possible, which was twenty percent less than the long-term average for the month, and January sunshine was the lowest ever recorded at Blue Hill. Also, there were 14 days with no bright sunshine, which tied as the second most ever observed in January.
BHO January Warmest Approximated 24-Hour Mean Temperature, deg F (1886-2023):
1) 35.6 in 1913
2) 35.0 in 1932
35.0 in 2023
4) 34.6 in 1937
5) 33.9 in 2006
6) 33.8 in 1933
33.8 in 1950
33.8 in 1990
BHO January Warmest Average Maximum Temperature, deg F (1886-2023):
1) 44.3 in 1913
2) 42.9 in 1937
3) 42.2 in 1932
42.2 in 1950
5) 42.0 in 1933
6) 41.7 in 1990
7) 41.6 in 2023
8) 41.5 in 2006
BHO January Warmest Average Minimum Temperature, deg F (1886-2023):
1) 29.1 in 2023
2) 28.7 in 1932
3) 28.0 in 2002
4) 27.7 in 1913
5) 27.2 in 1937
6) 26.9 in 2006
7) 26.6 in 1990
8) 26.5 in 1933
BHO January Highest Monthly Minimum Temperature, deg F (1886-2023):
1) 18 in 2023
2) 17 in 2002
3) 12 in 1937
12 in 1990
5) 11 in 1891
11 in 1932
7) 10 in 1949
10 in 1953
BHO January Highest Average Water Vapor Pressure, mb (1889-2023):
1) 6.0 in 2023
2) 5.6 in 1913
5.6 in 1932
4) 5.5 in 1937
5.5 in 1950
5.5 in 1995
7) 5.3 in 2006
8) 5.1 in 1933
BHO January Greatest Number of Days with Measurable Precipitation, (1886-2023):
1) 20 in 1950
20 in 2023
3) 18 in 1909
18 in 1911
18 in 1912
18 in 1917
18 in 1923
18 in 1932
18 in 1979
BHO Greatest Monthly Number of Days with Measurable Precipitation (1886-2023):
1) 24 in July 2021
2) 22 in December 1972
3) 21 in May 1888
21 in May 2019
5) 20 in July 1906
20 in April 1912
20 in October 1913
20 in June 1916
20 in April 1929
20 in January 1950
20 in May 2005
20 in April 2019
20 in October 2019
20 in January 2023
BHO January Lowest Mean Wind Speed, mph (1886-2023):
1) 11.4 in 2023
2) 11.7 in 2021
3) 12.2 in 2001
4) 12.8 in 2011
12.8 in 2020
6) 13.0 in 2022
BHO January Lowest Bright Sunshine, hours (1886-2023):
1) 73.2 in 2023 (26%)
2) 87.1 in 1950 (31%)
3) 88.1 in 1937 (31%)
4) 91.2 in 1909 (32%)
5) 91.8 in 1998 (32%)
6) 93.2 in 1954 (33%)
7) 94.0 in 1914 (33%)
8) 95.8 in 1979 (34%)
BHO January Greatest Number of Days Without Bright Sunshine (1886-2023):
1) 17 in 1956
2) 14 in 1952
14 in 2023
4) 13 in 1907
13 in 1930
13 in 1958
Mike Iacono
Chief Scientist
Blue Hill Observatory
