Alameda County Hydrology

Current and Forecasted Weather

by the National Weather Service

Current Radar    |    Bay Area Forecast Discussion

Local Forecast:  Oakland, Hayward, Fremont, Livermore

Watches, Warnings or Advisories for Alameda County

North Pacific Weather Models

North American Mesoscale (NAM)   |   Global Forecast System (GFS)

Rain Data Daily Log

Amount of precipitation accumulated over 24-hours as measured and reported by an observeruseful for validating and calibrating mechanical gauge stations.

Do you maintain a daily precipitation log?  Let us know!

Daily Observation Gauges

Oakland


Hayward


Fremont

Rain Data Incremental Recording

Mechanical gauge stations that report precipitation either as:

WEST COUNTY

Berkeley area


Oakland


San Leandro


Fremont

Streamflow Data

Gauge stations where runoff depth is measured and flow rate is calculated. 

Alameda Creek Watershed


San Lorenzo Creek Watershed

Tide Data

East Bay NOAA Stations measuring tidal elevations.

NOAA Tide Stations


Mean Annual Precipitation

The red lines on the map above are isohyet lineslines connecting points having the same amount of rainfall in a given period. On this map, the lines are connecting points of equal rain over the course of a year, not any specific year, but an average year based on the arithmetic mean for a 125-year dataset. 

These isohyets make up Alameda County's latest mean annual precipitation map updated in 2011 by the Alameda County Flood Control and Water Conservation District with the help of Alaco Engineering.  These data are the foundation of storm calculations performed using the criteria of the District's Hydrology and Hydraulics Manual.

Click/tap on a line to view the mean annual precipitation value for that location.

Individual Storm Analysis

An in depth look at some past rainfall events in Alameda County that were significant for their intensity and/or overall magnitude. Paired with stream flow measurements, these data can be used to calibrate and test the validity of computer models that simulate the local rainfall to runoff relationship.

2022, Dec 31     |     2014, Dec 11*     |     2014, Mar 25*     |     2011, Mar 24*     |     2010, Dec 19*     |     2009, Oct 13*     |     1998, Feb 02*             *Requires Log-In

Major Watersheds

Alameda Creek     |     San Leandro Creek     |     San Lorenzo Creek