The phrase "It never rains, but pours" is used to convey the thought that when something hasn't happened in quite sometime, happens again in large amounts.

Weeks ago dry conditions resulted in the smoke from forest fires drifting across huge swaths of Canada all the way to the USA eastern seaboard. Weather conditions can and do have rapid changes and that's what has happened in our area. We have received a huge amount of rain locally the past week causing the river to rise to dangerous levels. 

The rain has has helped with the forest fires and the drought conditions on farms to some extent but for some of the forest fires and many farms its either its still dry here of way too much, too late.