Cliff Mass has an excellent post on our wet weather at his blog: Cliff Mass Weather Blog
A Year's Worth of Water in 5 Months
Meteorologists and hydrologists call it the water year, the period between October 1 and September 30. Each year the cumulative precipitation for the water year is totalled starting October 1.
The water year is a natural precipitation measure along the U.S. West Coast because we typically get very little precipitation over the summer and precipitation generally is not significant until October.
Thus, there is a hydrological reset each summer, with the soils dried, the snowpack melted, and the rivers dropping to low early fall levels. So October 1 is a good date to start the new water season.
Now the amazing thing. Five and one-half months into the 2016-2017 water year, many Northwest stations have ALREADY received their total water year amounts. You got that right....if there was not another drop of rain or flake of snow for the next 6.5 months, these stations would have their full normal precipitation for the water year.
Yep - wet!