Frequently Asked Questions (FAQ)

Is all of the LA basin and surrounding mountains on the 10/1 to 9/30 rain year? How was this timeframe chosen? The TV weather man says its 7/1 to 6/31. Thank you.

Rainfall records for the Los Angeles basin and it's surrounding mountain areas are on the October 1st to September 30th "Water Year" time frame.

The USGS, National Weather Service and hydrologists' community have chosen this time frame as the official "Water Year". Any hydrology text defines a water year within this time frame.

The July 1st to June 30th corresponds to a "Fiscal Year" and should not be used for "Water Year".

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