February 2018 Summary – Warmest on Record – Blue Hill Observatory & Science Center

Blue Hill Observatory February 2018 Summary: February was exceptionally warm with near average rainfall and less snow than normal. The 24-hour adjusted mean temperature for the month of 36.1 deg F was 9.7 degrees warmer than the 120-year average for February and 7.0 degrees warmer than the 1981-2010 30-year average. The month was the warmest February on record with a mean that surpassed the previous record, 34.9 deg F in 1984, by more than a degree. The February departure from the 120-year mean is the third highest positive temperature departure for any month of the year on the entire period of record at the Observatory. February was so warm that it was also 1.7 deg F warmer than the long-term average temperature for March, which has only happened once before since 1885. Twenty-three days were warmer than normal, and the 21st, with a high of 70F, a low of 50F, and a mean of 60F was the warmest February day, in terms of the mean, ever measured at Blue Hill. The 70F on the 21st was the high for the month, it was a new record for the date surpassing 62F in 1930, it was the earliest observation in any year of a temperature of 70F or more, and it was the second highest reading in February behind only 71F observed just last year on 24 February 2017. The minimum on the 21st of 50F was a new record high minimum for the date, surpassing 45F in 2002, and a new record high minimum for February, surpassing 49F on 21 February 1981. The low temperature during February was 4F on the 3rd. The average maximum temperature of 45.1 deg F was also a new record for February, and the average minimum of 27.3 deg F was the second warmest ever observed. A total of 4.12 inches of precipitation was measured during the month, which was only slightly more than the long-term 120-year average and the 30-year mean. The greatest in 24 hours was 0.86 inches during a rain storm on the 10th-11th. Snowfall totaled 10.2 inches, which was six inches less than the long-term mean and four inches less than the 30-year average. More than half of this amount, 5.8 inches, occurred on the 18th, which was also the largest snowfall in 24 hours. Due to the low snowfall and the excessive warmth, only six days during the month had a trace or more of snow on the ground. Also due to the warmth, Ponkapoag Pond was observed to be fully thawed on the 20th. A highlight of the month was a maximum sea-level pressure of 30.83 inches on the 13th, which was the highest pressure at the Observatory since 30.88 inches was recorded on 25 November 2015, and it was the highest pressure in February since the station record sea-level pressure of 31.08 inches was observed on 13 February 1981. February mean vapor pressure, which is a measure of moisture in the air, was a new record for the month at 5.9 mb surpassing the previous record of 5.8 mb in 1981. The mean wind speed for February was 12.8 mph, which was the fourth lowest on record, and the prevailing direction was from the west-northwest. A peak gust of 47 mph from the west-northwest occurred on the 5th. February was much cloudier than average with 120.2 hours of bright sunshine, or 42 percent of the possible, which was eight percent less than the long-term mean. BHO Warmest February 24-Hour Adjusted Mean Temperature, deg F (1885-2018): 1) 36.1 in 2018 2) 34.9 in 1984 3) 34.3 in 2012 4) 34.0 in 1998 5) 33.9 in 1954 33.9 in 1981 7) 33.8 in 2017 8) 33.7 in 1976 BHO February Warmest Average Maximum Temperature, deg F (1885-2018): 1) 45.1 in 2018 2) 44.0 in 1976 3) 43.5 in 1981 4) 43.2 in 1984 43.2 in 2017 6) 43.0 in 2012 7) 42.9 in 1954 42.9 in 2002 BHO February Warmest Average Minimum Temperature, deg F (1885-2018): 1) 27.9 in 1998 2) 27.3 in 2018 3) 27.1 in 1984 4) 26.4 in 2012 5) 26.3 in 1925 6) 26.2 in 1954 7) 25.7 in 1981 8) 25.5 in 1997 25.5 in 2017 BHO Highest Monthly Mean Temperature Departures Relative to 120-Year Mean, deg F (1885-2018): 1) +13.1 in December 2015 2) +9.9 in January 1913 3) +9.7 in February 2018 4) +9.3 in January 1932 5) +9.1 in March 1946 6) +9.0 in March 2012 7) +8.9 in January 1937 8) +8.5 in February 1984 BHO Warmest February Daily Maximum Temperature, deg F (1885-2018): 1) 71 on 24 Feb 2017 2) 70 on 21 Feb 2018 3) 68 on 24 Feb 1985 68 on 25 Feb 2017 68 on 20 Feb 2018 6) 67 on 26 Feb 1957 67 on 25 Feb 1976 67 on 23 Feb 2017 9) 66 on 20 Feb 1930 66 on 19 Feb 1981 BHO Warmest February Daily High Minimum Temperature, deg F (1885-2018): 1) 50 on 21 Feb 2018 2) 49 on 20 Feb 1981 3) 48 on 20 Feb 2018 4) 47 on 28 Feb 1910 47 on 23 Feb 1990 47 on 24 Feb 2017 7) 46 on 26 Feb 1957 8) 45 on 22 Feb 1954 45 on 5 Feb 1991 45 on 21 Feb 2002 BHO Highest February Mean Vapor Pressure, mb (1932-2018): 1) 5.9 in 2018 2) 5.8 in 1981 3) 5.5 in 1984 4) 5.1 in 1998 5) 5.0 in 2016 6) 4.9 in 1954 7) 4.8 in 2017 BHO February Lowest Mean Wind Speed, mph (1885-2018): 1) 12.6 in 2014 2) 12.7 in 2005 12.7 in 2012 4) 12.8 in 2018 5) 13.0 in 1986 6) 13.5 in 2015 7) 13.8 in 2008 Mike Iacono Chief Scientist Blue Hill Observatory