April 2018 Summary – Colder and Wetter Than Average

Blue Hill Observatory

April 2018 Summary:

April was notable for being cooler than average until the last week with more precipitation than average. The 24-hour adjusted mean temperature for the month of 43.1 deg F was 1.6 degrees cooler than the 120-year average for April and more than three degrees cooler than the 1981-2010 30-year average. It was the coolest April since 2003, which averaged 42.4 deg F. The warmest temperature for the month was 73F on the 28th, and the coldest temperature was 24F on the 9th. The last freezing temperature of the season of 31F occurred on April 20th. A total of 6.51 inches of precipitation was measured during the month, which was about two and a half inches more than the long-term 120-year average and about two inches more than the 30-year mean. Nearly half of the monthly total, 2.95 inches, fell during a chilly rain storm on the 15th-16th, which also brought a trace of snowfall and wind gusts from the ENE to 41 mph. The greatest precipitation in 24 hours was 2.85 inches on the 15th-16th. Snowfall for April totaled 2.6 inches, which was slightly less than average, bringing the seasonal total to 92.8 inches, which was about 30 inches more than the long-term average and the 30-year normal. The final measurable snowfall of the season was 1.0 inches on April 6th. The mean wind speed for the month was 12.6 mph, which was the fourth lowest on record, and the prevailing direction was from the west-northwest. A peak gust of 56 mph from the northwest occurred on the 4th. April was much cloudier than average with a total of 162.4 hours of bright sunshine or 42 percent of possible, which was seven percent less than the long-term mean.

BHO Lowest April Mean Wind Speed, mph (1885-2018):

1) 12.0 in 2008
2) 12.3 in 2010
3) 12.4 in 2001
4) 12.6 in 2018
5) 12.7 in 1998
6) 12.8 in 1986
12.8 in 2017

Mike Iacono
Chief Scientist
Blue Hill Observatory