April 2017 Summary – Third Warmest on Record

Blue Hill Observatory

April 2017 Summary:

April was generally warm with a few cold periods and was much wetter than average. The 24-hour mean temperature for the month of 50.1 deg F was 5.4 degrees warmer than the 120-year average for April and nearly four degrees warmer than the 1981-2010 30-year average. The month ranked as the third warmest April on record, and it was the warmest since 2010. The average maximum temperature for the month of 60.6F was the fifth highest on record, and the average minimum temperature of 41.3F was the third warmest on record. April was more than 18 deg F warmer than March, which is a difference that has only been surpassed twice before, in 1941 and in 1885. The month began close to the average temperature then became periodically warmer with the temperature reaching the 80’s several times. The highest temperature of the month was 86F on the 16th, which was not a daily record, though the high of 85F on the 11th surpassed the previous record of 78F set in 1945. The coldest temperature during April and the last freeze was 30F on the 2nd. The April water vapor pressure, which is a measure of water in the air, was 8.1 mb, which tied for the 2nd highest April value since 1932. A total of 6.69 inches of precipitation was observed, which was more than two and a half inches more than the long-term 120-year average and a little more than two inches greater than the 30-year mean. April was the 11th wettest on record since 1885. The greatest amount in 24 hours was 2.21 inches on the 1st, which included the only measurable snowfall of the month of 2.7 inches. A rain storm on the 6th brought 1.27 inches of rain and the only thunderstorm of the month. Snowfall for April totaled 2.7 inches, which was slightly less than the long-term mean and the 30-year normal. The seasonal snowfall of 66.4 inches was slightly more than five inches higher than the 120-year mean of 61 inches. The mean wind speed was 12.8 mph, which tied for the fifth lowest on record for April, and the prevailing direction was from the south. The peak gust was 43 mph from the south-southwest on the 7th and 43 mph from the west-northwest on the 29th. April sunshine was exactly average with 189.3 hours, or 49 percent of the possible bright sunshine.

BHO Warmest April 24-Hour Mean Temperature, deg F (1885-2017):

1) 51.5 in 2010
2) 51.0 in 1976
3) 50.1 in 2017
4) 49.9 in 2012
5) 49.4 in 1945
6) 49.0 in 1994
7) 48.9 in 2005
   48.9 in 2009

BHO Warmest April Average Maximum Temperature, deg F (1885-2017):

1) 62.4 in 1976
2) 62.2 in 2010
3) 61.8 in 2012
4) 61.2 in 1945
5) 60.6 in 2017
6) 60.4 in 1941
7) 60.3 in 1991

BHO Warmest April Average Minimum Temperature, deg F (1885-2017):

1) 41.8 in 2010
2) 41.5 in 1945
3) 41.3 in 2017
4) 40.5 in 1910
5) 40.4 in 1976
6) 40.1 in 2012
7) 39.9 in 2011

BHO Largest April-March 24-Hour Mean Temperature Difference, deg F (1885-2017):

1) +20.6 in 1885 [44.3 / 23.7] 2) +19.1 in 1941 [48.7 / 29.6] 3) +18.5 in 2017 [50.1 / 31.6]
4) +17.5 in 1915 [47.3 / 29.8] 5) +17.4 in 1896 [45.4 / 28.0]

BHO Highest April Water Vapor Pressure, mb (1932-2017):

1) 8.6 in 1945
2) 8.1 in 1993
   8.1 in 2011
   8.1 in 2017
5) 8.0 in 1974
6) 7.9 in 1973
   7.9 in 2002

BHO Lowest April Mean Wind Speed, mph (1885-2017):

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

Mike Iacono
Chief Scientist
Blue Hill Observatory