Contra Costa County
QPF Maps
Look for Data Plots under "More".
11 Year Data Plot (updated 5/24/17)
Data Layers
Show Data
Show Symbols for Sites with no Rain
Show Symbols for Sites with Missing Data
Contra Costa County Boundary
All County Boundaries
NWS Warnings
NWS Warning Statements
NWS Warning Legend
NHC Hurricane/Trop Storms Forecasts
NWS Radar Sites

NWS Radar Products
Radar layer Off
Short-Range Reflectivity (N0R)
Long Range Reflectivity (N0Z)
Composite Reflectivity (NCR)
National Mosaic Radar
High Resol. Base Radar Reflectivity (N0Q)
Loop Radar Product
      Opacity:  25% 50% 75%
       Speed:   Slow       Fast

This site provides:

We collect the data from the stations every 20 minutes and update the map every 20 minutes.

Use the Datasets Menu to change rainfall period or select water level or battery voltage.

Use the Layer/Radar Menu to change which layer or radar product is shown.

This website works best in Chrome and Firefox. It may have display issues in Internet Explorer.

The NWS Radar Products (layers) are imported to this Gmap from the NWS and are not generated by the Contra Costa County Flood Control and Water Conservation District.

Detailed information about the layers can be found through the National Oceanic and Atmospheric Administration (NOAA).

Why does the N0Q radar mode show rain when it's not raining?
When it is not raining, the NOAA NEXRAD radars go into "Clear Air Mode" where their sensitivity increases. It then detects airborne dust and particulate matter. Rotating wind turbine blades can also impact radar readings. We see their impact in the the areas west of Rio Vista and around Altamont Pass. See this NOAA webpage for more information about wind turbines.

Go to the Legend for more information about the different radar layers.

If you are interested in how radar works, go to this website.

For a historic radar go to this website.

Rainfall, Water Level, and Battery voltage
 = No precipitation has occurred in the select time period.
 = Data missing, gauge has not reported in last 24 hours.

Point color: Point color will change when 7-5-3 protocols are met. Click 7-5-3-2 menu or icon for more information.

Radars: For detailed descriptions of the radar products, search for the three letter Product ID on the National Oceanic and Atmospheric Administration (NOAA) website.

Product ID "N0R" = Short-Range Reflectivity
Product ID "N0Z" = Long Range Reflectivity
Product ID "NCR" = Composite Reflectivity
Product ID "N0Q" = High Resolution Base Radar Reflectivity

Clicking a blue "+" or a data label will open a window with station information, a table of data, and a plot.

The table cell colors for the 7-day, 30-day and Season amounts will change when the 7-5-3 protocols are met. See Flood Forecasting 7-5-3-2 in the Info menu list.

Storm rainfall resets at each gauge after 12 hours without rain.

The battery plots with flat voltage lines are for stations with batteries charged using household current. The battery plots with wavy voltage lines are for stations with batteries charged using solar panels. They gain or lose charge with the sunshine.

One of the most common station maintenance issues is battery charging failure which can be due to a variety of reasons.

The "Dataset:" and "Update:" text will turn red if it has been more than 1 hour since the last data update.

When the watersheds are wet, there is more chance of flooding when a big storm comes. We can look at past rainfall to get an idea of how wet the watersheds are.

A table pops up when you click on a rain data point (blue "+" or data number). The table shows you the rain that has fallen so far in the season, in the last 30-days, and in the last 7-days. When the rain depths are around 7", 3", and 5" respectively, and if we have a forecast of 2" of rain in the next 24 hours (see 24-hour QPF map), you should expect some level of flooding.

You can find out more about the 7-5-3-2 protocols at our Flood Forecast Information Page. Click the image below.

You may click the location marker to zoom in and center on it. It may be dragged to another location.

The location is not saved, but is updated to your current location on refresh.

The marker is an approximation of your location based on information from your device. The location is only as good as your device provides and may not be accurate or precise, and is only updated when you refresh the webpage. Sometimes a computer connected to a larger network will show a location of a main server for the system and not your computer.