Massachusetts’s Precipitation Record
The official 24-hour rainfall record for the state of Massachusetts is 18.15 inches observed at Westfield, MA (Hampden County) on August 18-19, 1955 was a result of Hurricane Diane. The extreme rainfall produced by Diane caused widespread flooding across portions of New England.
Source: Diane 1955 Floods | WikiMedia
Did You Know?
In August 1955, two named tropical systems impacted southern New England and caused significant flooding across the region. Hurricane Connie produced up to 7 inches of rain over parts of Massachusetts on August 11th and 12th; saturating the ground and raising stream levels prior to the heavy rainfall from Hurricane Diane, a week later.