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 observer—useful for validating and calibrating mechanical gauge stations.
Do you maintain a daily precipitation log? Let us know!
Daily Observation Gauges
Oakland
test 1
test 2
Hayward
test 3
test 4
Fremont
test 5
test 6
Rain Data • Incremental Recording
Mechanical gauge stations that report precipitation either as:
an event of accumulated incremental depth, such as 0.01 inches or 1-mm, or
depth accumulated during an increment of time, such as every 15-minutes.
WEST COUNTY
Berkeley area
Tilden Park - TLD (hourly) - operator: Contra Costa County
Oakland
Oakland North - ONO (hourly)
Oakland Museum - OKM
Oakland South - OSO (hourly) - operator: Oakland Fire Services Agency
San Leandro
San Leandro Marina - SLE (event) - operator: ACFC&WCD
Fremont
Mission Peak - MSP (event) - operator: National Weather Service
Streamflow Data
Gauge stations where runoff depth is measured and flow rate is calculated.
Alameda Creek Watershed
Alameda Creek below Calaveras Creek near Sunol - USGS 11173510
Alameda Creek above Diversion Dam near Sunol - USGS 11172945
Alameda Creek below Diversion Dam near Sunol - USGS 11172955
Alameda Creek near Niles - USGS 11179000
Alameda Creek near Fremont - USGS 11179100
Alameda Creek Flood Control Channel at Union City - USGS 11180700
San Lorenzo Creek Watershed
Tributary to San Lorenzo Creek | Crow Creek near Hayward - USGS 11180900
Tributary to San Lorenzo Creek | Cull Creek above Cull Reservoir - USGS 11180960
Tributary to San Lorenzo Creek | Chabot Creek at Strobridge - ACFC&WCD
Tributary to San Lorenzo Creek | Castro Valley Creek at Watson - ACFC&WCD
Tributary to San Lorenzo Creek | Castro Valley Creek at Hayward - USGS 11181008
San Lorenzo Creek above Don Castro Reservoir - USGS 11180825
San Lorenzo Creek at Don Castro Dam - ACFC&WCD
San Lorenzo Creek at Hayward - USGS 11181000
San Lorenzo Creek below Washington - USGS 11181040
Mean Annual Precipitation
The red lines on the map above are isohyet lines—lines 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