December 2018 Summary – Warmer and Sunnier Than Average

| January 9, 2019 | Reply

Blue Hill Observatory

December 2018 Summary:

December was warmer and drier than average with very little snowfall and abundant sunshine. The 24-hour adjusted mean temperature for the month of 33.3 deg F was 3.5 degrees warmer than the 120-year average for December and 1.7 degrees warmer than the 1981-2010 30-year average. The average maximum temperature of 40.6 deg F was nearly two degrees warmer than normal, and the average minimum temperature of 25.8 deg F was more than one degree above normal. The highest temperature for the month of 62F on the 21st surpassed the previous record for the date of 60F set in 1957. The lowest temperature was 15F on the 8th, which was among the warmest monthly minimum temperatures in December on record and reflects the absence of extreme cold during the month. Precipitation totaled of 3.84 inches during December, which was about a half inch drier than the long-term 120-year average and about an inch less than the 30-year mean. The greatest amount in 24 hours was 1.04 inches during a warm rain storm on the 2nd. December was remarkable for bringing only 0.1 inches of snowfall, which was 11 inches less than the long-term mean and among the lowest December totals on record. There were no thunderstorm days during the month leaving the annual total at 24, which was two more than average. Due to the warmth and frequent sunshine, the two local ponds, which fully froze for a short time, had only partial ice cover for much of the month. The mean wind speed was 12.4 mph, and the prevailing direction was from the NW. A peak gust of 60 mph from the south-southeast occurred on the warmest day of the month during heavy rain on the 21st. December had much above average sunshine, with 161.4 hours of bright sunshine, or 59 percent of possible, which was 13 percent more than the long-term mean of 46 percent. December was the eighth sunniest on record.

BHO Highest December Monthly Minimum Temperature, deg F (1885-2018):

1) 23 on December 29 and 30, 2015
2) 18 on December 31, 2001
3) 17 on December 8, 2006
   17 on December 31, 2012
5) 15 on December 2, 1907
   15 on December 8, 2018

BHO Lowest December Snowfall, inches (1885-2018):

1) Trace in 1899
   Trace in 1953
   Trace in 1999
   Trace in 2011
5) 0.1 in 1943
   0.1 in 2018
7) 0.2 in 1936
   0.2 in 1957

BHO Highest December Bright Sunshine, hours (1886-2018):

1) 184.7 in 1960 [67%]
2) 172.7 in 1989 [63%]
3) 171.3 in 2000 [62%]
4) 165.5 in 1899 [60%]
5) 163.9 in 1947 [60%]
6) 163.8 in 1955 [60%]
7) 162.5 in 1896 [59%]
8) 161.4 in 2018 [59%]
9) 161.0 in 1909 [59%]
10) 158.4 in 1999 [58%]

Mike Iacono
Chief Scientist
Blue Hill Observatory

Category: Weather Summary Archives

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