Contra Costa County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Contra Costa County: 0.
2. Weak tornadoes were under-recorded before Doppler radar coverage became national in the early 1990s, so earlier decades read low. Ratings use the Fujita scale before February 2007 and the Enhanced Fujita scale after.

Storm Prediction Center severe weather database, 1950 to 2025.

Every large fire

1. Large fires mapped by the Monitoring Trends in Burn Severity program since 1984: 1,000 acres or more in the West, 500 or more in the East. Prescribed burns are excluded. Acres here are the part of each perimeter inside this place.

Monitoring Trends in Burn Severity (USGS and U.S. Forest Service), 1984 to 2026.

Smoke overhead

1. A smoke day is a date on which a smoke plume traced by NOAA Hazard Mapping System analysts from satellite imagery covered this place's point (the county's population centre or the city centre). Counts here are of medium or heavy smoke. Since 2018 analysts have often drawn light smoke as one area over most of the continent, so light-smoke counts are not comparable from year to year. The plumes show smoke anywhere in the air above, not air quality at the ground, and smoke hidden by cloud is missed.

NOAA Hazard Mapping System smoke analysis, 2011 to 2026, retrieved October 30, 2026.

Claims by ZIP code

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026. NOAA Storm Events through 2026.

River crests

The National Weather Service sets flood stages for 1 gauge here but lists no crests for it.

River gauges

1. Crests are the highest and the recent crests the National Weather Service lists for each river gauge in the county that has a flood stage, not every flood. Flood categories use each gauge's current flood stages; crests from before levees, dams or channel changes may not be comparable. Crests measured on an old datum are left out of the rankings.

NOAA National Water Prediction Service gauge records, retrieved October 30, 2026.

High tide flooding

1. High tide flooding days are days on which a NOAA tide gauge recorded water at or above NOAA's minor flood threshold, set from the gauge's tide range, counted by meteorological year (May to April). These are the counts in NOAA's annual high tide flooding reports; they are not National Weather Service flood stages. Years with less than 80 percent of data are left out.

NOAA CO-OPS high tide flooding counts, through April 2026, retrieved October 30, 2026.

1. The Palmer Drought Severity Index is computed by NOAA each month from the county's average temperature and precipitation, relative to the county's own climate. Zero is normal; -3 or lower is severe drought and -4 or lower extreme drought. It describes the long-term balance of moisture, not water supply or crop losses.

NOAA NCEI nClimDiv county Palmer Drought Severity Index, 1895 to September 2026, issued October 6, 2026.

Every earthquake of magnitude 4 or more within 50 miles

1. Earthquakes of magnitude 2.5 or more in the USGS Comprehensive Catalog since 1900. Within 50 miles means the epicentre lies within 50 miles of the county boundary (or inside the county).
2. Small earthquakes were under-recorded before the modern seismic networks of the 1970s and are still missed in remote areas, so early decades read low. Magnitudes are as the catalogue reports them and mix scales (moment, local and body-wave).

USGS ANSS Comprehensive Earthquake Catalog, 1900 to present, retrieved October 30, 2026.

Tsunamis

1. Places where NOAA's Global Historical Tsunami Database records a tsunami's water arriving, with the greatest height it reached above sea level at the time. Only tsunamis NOAA rates probable or definite are counted. Heights from eyewitness accounts and tide gauges are mixed, and older events are less completely recorded.

NOAA NCEI/WDS Global Historical Tsunami Database, retrieved October 30, 2026.

Volcanoes within 100 miles

1. U.S. volcanoes within 100 miles, from the USGS Volcano Hazards Program. The threat category is the USGS 2018 National Volcanic Threat Assessment, which ranks volcanoes by how hazardous their past eruptions were and how many people and how much infrastructure lie near them. It is not a forecast of eruption.

USGS Volcano Hazards Program, retrieved October 30, 2026.

Mapped landslides

Mapped by USGS CA East SF Bay 2016-2017 (11,267), CA GS (3,042), USGS CA Crow Creek 1998 (734), USGS Earthquake-Triggered Ground Failure (50), USGS CA SF Bay Dec 2022 - Jan 2023 (17), NASA (12) and 1 more.

1. Landslides mapped in the USGS compilation of landslide inventories across the United States (version 3.0, 2025), rated probable or better. The compilation joins inventories made by federal and state agencies for different purposes and areas, so the number mapped in a county reflects how closely it has been surveyed as much as how often its slopes fail. An area with few records may simply not have been mapped. Deaths are as recorded in the inventories; a slide listed in two inventories is counted once.

USGS Landslide Inventories across the United States, version 3.0, retrieved October 27, 2026.

More event types since 1996

Costliest events since 1996

1. Jan 1, 2006Flood$22.0 million
   National Weather Service narrative

   Widespread flooding continued into early 2006 after very heavy rains through December 31st brought 3 to 4 inches in a 24 hour period. Urban flooding initiated landslides that contributed to the damage, and small streams and creeks overflowed their banks. Much of the damage was in Walnut Creek, Richmond, San Pablo, Martinez and Orinda. Included in the damages were schools, park areas and several Government Buildings.

2. Dec 31, 2005Flood$22.0 million
   National Weather Service narrative

   Widespread county flooding occurred after 2 to 4 inches of rain fell on the area in about 24 hours. Urban flooding initiated landslides that contributed to the damage, and small streams and creeks overflowed their banks. Much of the damage was done in Walnut Creek, Richmond, San Pablo, Martinez and Orinda. Included in the damages were schools, park areas and several Government Agency structures. Approximately 165 personal assistance claims due to flooding were filed within the County. Flooding persisted into the first few days of January 2006.

3. Apr 6, 2006Debris Flow, East Bay Interior Valleys$11.0 million
   National Weather Service narrative

   Strong April storms brought heavy rain to much of Alameda County. Landslides, eroding hillsides and cracked pavement was the result of the persistent rainfall - prompting nearly $10 million damage to county roadways. Oversatureated earth also caused landslide or erosion problems on private properties which spilled over onto county rights-of-way.

4. Oct 13, 2009High Wind, San Francisco Bay Shoreline$2.5 million
   National Weather Service narrative

   High winds were reported throughout San Francisco Bay shoreline. Here are other measured peak wind gust reports from automated systems: Point San Pablo Bay Area Air Quality Management District - 74 mph and San Francisco Airport - 62 mph. The high winds knocked down power lines and trees causing hundreds of thousands of people to lose power. A huge oak tree crushed a house in Redwood City and brought down power lines. Also in Redwood City, dozens of trees were toppled, including at least two that hit houses or parked cars. Within San Mateo County at least 47 trees and 31 sets of power lines were knocked over. In Los Altos, three power lines and 18 trees were knocked down. Several…

5. Mar 24, 2011Debris Flow, East Bay Interior Valleys$1.6 million
   National Weather Service narrative

   A landslide in the City of San Pablo affected six homes and two city parcels. The area affected was along Wyman Street and Hillcrest Road. Throughout Contra Costa County, nearly $16 million worth of damage occurred due to the March storms.

6. Dec 2, 2011Strong Wind, East Bay Interior Valleys$1.3 million
   National Weather Service narrative

   Wind has been blamed for spreading a fire that damaged 10 condominium units in the Walnut Creek area (200 block of County Brook Loop near Alcosta Blvd). Four other two bedroom condos had less serious damage. One resident was injured when they jumped out of their burning condo to the ground. The cause of the fire is unknown, but wind played a large part in spreading the fire.

7. Oct 24, 2016Strong Wind, San Francisco Bay Shoreline$1.0 million
   National Weather Service narrative

   An 80-foot elm tree, three feet in diameter, was blown down in Berkeley and landed on an apartment building on College Avenue near Alcatraz Ave. No one was hurt and there was minimal structural damage.

8. Dec 1, 2011Strong Wind, East Bay Interior Valleys$400,000
   National Weather Service narrative

   High winds were blamed for speeding a fire that destroyed two homes and damaged a third in North Livermore near May Nissen Park. Even though the fire's cause is under investigation high winds had a significant effect on this event.

9. Jan 20, 2010Strong Wind, East Bay Interior Valleys$280,000
   National Weather Service narrative

   Strong winds toppled two large trees, a Coastal Redwood and a spruce, on Valley Avenue just west of Santa Rita Road in Pleasanton causing damage to a block wall. Also in Pleasanton, power lines were damaged by strong winds on Spring Street and on Valley Avenue. In Alamo, a centuries-old oak tree detached from its muddy soil and came to rest on a Deodar Lane home causing extensive damage. In Martinez, A tree fell along Alhambra Valley Road, between Castro Ranch and Bear Creek Road, taking power lines down with it. Also, in Orinda, power lines were blown down near La Espiral.

10. Dec 2, 2012Flood$250,000
    National Weather Service narrative

    During heavy rainfall, a 24 inch culvert failed and collapsed, opening up a 20 foot sinkhole on Tarabrook Drive. One lane of traffic could still get by the sinkhole. The Orinda City Council declared a state of emergency due to this large sinkhole.

1. Storm Events records before 1996 cover only tornadoes, thunderstorm wind and hail. Damage figures are as reported by the National Weather Service at the time, not adjusted for inflation.

NOAA NCEI Storm Events Database, 1950 to 2026, issued October 26, 2026.

All-time high

104°FSep 6, 2020

All-time low

25°FJan 5, 1949

Warmest night

69°FAug 14, 2020

Coldest day

38°FDec 9, 1972

Wettest day

5.01 inDec 31, 2022

Snowiest day

1.0 inFeb 5, 1976

Hottest year

2020mean 61.2°F

Coldest year

1955mean 55.1°F

Wettest year

197329.37 in

Driest year

20134.89 in

Station Oakland International Airport (USW00023230), 5 ft elevation, 18.8 miles from the population centre. Daily records from 1948 to October 26, 2026; 89.1% of days in the last 30 years are complete. Records at a single station can differ from a city’s official threaded record, which may combine several stations.

NOAA NCEI Global Historical Climatology Network Daily.

This product uses the Federal Emergency Management Agency's OpenFEMA API, but is not endorsed by FEMA. The Federal Government or FEMA cannot vouch for the data or analyses derived from these data after the data have been retrieved from the Agency's website(s).

OpenFEMA Disaster Declarations Summaries, retrieved October 30, 2026. Statewide declarations are not listed.

Neighbouring counties

• Tornadoes NOAA Storm Prediction Center severe weather database, through 2025.
• Tropical cyclones NOAA National Hurricane Center HURDAT2 (Atlantic; Northeast and Central Pacific), through 2025.
• Wildfire USGS/USFS Monitoring Trends in Burn Severity, through 2026.
• Storm events NOAA NCEI Storm Events Database, through 2026.
• Flood insurance OpenFEMA NFIP Redacted Claims v3, refreshed August 4, 2026.
• Declarations OpenFEMA Disaster Declarations Summaries v2, retrieved October 30, 2026.
• Weather records NOAA NCEI Global Historical Climatology Network Daily, station USW00023230.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, retrieved October 30, 2026.
• Tide gauges NOAA CO-OPS high tide flooding counts, retrieved October 30, 2026.
• Drought NOAA NCEI nClimDiv county Palmer Drought Severity Index, through September 2026.
• Smoke NOAA NESDIS Hazard Mapping System smoke analysis, retrieved October 30, 2026.
• Tsunamis NOAA NCEI/WDS Global Historical Tsunami Database.
• Volcanoes USGS Volcano Hazards Program, U.S. volcanoes and 2018 threat assessment.
• Landslides USGS Landslide Inventories across the United States, version 3.0 (2025).
• Earthquakes USGS ANSS Comprehensive Earthquake Catalog (ComCat), retrieved October 30, 2026.

Joins, thresholds and known limits are set out in the methodology. Found an error? Report it. Page built October 30, 2026.