Overall, it is likely that there has been a 2 to 4 % increase in the number of heavy precipitation events when averaged across the mid - and high latitudes. (ipcc.ch)
However, combined measuring stations around the world suggest there has been a global trend towards more frequent and intense hot extremes since the 1950s, as well as more heavy precipitation events. (natureworldnews.com)
Since 1991, the amount of rain falling in very heavy precipitation events has been significantly above average. (nca2014.globalchange.gov)