October 2019 Summary – Second Cloudiest on Record

Blue Hill Observatory October 2019 Summary:

October was generally warm with much more rainfall and more clouds than average. The 24-hour adjusted mean temperature for the month of 53.3 deg F was 2.2 degrees warmer than the 120-year average for October and 1.9 degrees warmer than the 1981-2010 30-year average. The average maximum temperature of 60.5 deg F was 0.2 degrees above normal, and the average minimum temperature of 46.7 deg F was 3.8 degrees above normal. The warmest temperature for the month was 77F on the 7th, and the lowest temperature was 35F on the 5th. Precipitation totaled 6.92 inches, which was nearly three inches more than the long-term 120-year average and more than two inches more than the 30-year mean. The greatest precipitation in 24 hours was 1.96 inches on the 16th-17th. Most of this total fell in about four hours during the passage of a rapidly intensifying storm that brought strong winds and a record low minimum sea-level pressure for October of 28.82 inches early on the 17th. There were no thunderstorm days during October. The mean wind speed was 12.6 mph, and the prevailing wind direction for the month was from the northeast. A peak gust of 61 mph occurred twice, from the south on the 17th and from the east on the 31st. October was very cloudy with only 117.9 hours of bright sunshine, or 36 percent of possible, which was 20 percent less than the long-term average. October ranked as the 2nd cloudiest on record.

BHO Lowest October Sunshine, hours (1886-2019):

1) 80.5 in 1913  [24%] 2) 117.9 in 2019  [36%}
3) 120.3 in 1896  [36%] 4) 121.6 in 1919  [37%] 5) 124.9 in 1888  [38%]

BHO Lowest October Sea-Level Pressure, inches (1885-2019):

1) 28.82 on October 17th, 2019
2) 28.95 on October 25th, 1925
3) 29.03 on October 25th, 1926
   29.03 on October 28th, 2006
   29.03 on October 30th, 2017

Mike Iacono
Chief Scientist
Blue Hill Observatory