Precipitation and streamflow averaged above normal throughout Washington in the 1997 water year (October 1996 to September 1997). The description "above normal" refers to flow in the upper quartile, "below normal" refers to the lower quartile, and "normal" refers to the middle quartiles. Overall, the year was wetter than normal, with above-average precipitation for every month except February and August, which were below average. The most severe floods occurred on January 1 and March 19, producing peaks of record at several stations. Average to above-average snowpack in the mountains produced average to above-average streamflow throughout the summer at most gaging stations, with peaks of record on several rivers in the northeastern part of the state.

The 1997 water year contained many periods of high streamflow and three significant but localized flood events in a year of generally above-normal precipitation throughout Washington. In general, November, December, January and March received above-average precipitation throughout the state. The Cascade Range was wettest during the month of December, with some areas on the eastern slopes of the Cascade Range receiving (the snow equivalent of) up to 17 inches of rain and some areas on the western slopes receiving over 35 inches of rain (National Oceanic and Atmospheric Administration 1996). March was also a wet month for both the southern and western slopes of the Olympic Mountains and the western slopes of the Cascade Range. Some of the worst flooding in the state occurred in this region and in the urban areas of Puget Sound at the end of December and the beginning of January when freezing rain and snow were followed by more heavy rain. Many streamflow stations reached their peaks fir the year during the "New Year's Flood event". For some stations, however, the highest peak was recorded in March during an unusually strong spring storm. In northeastern Washington, the rapid melting of heavy snopack caused peak-of-record flow in June. The driest months of the water year were July and August.

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