Tuolumne County

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond the county. Deaths recorded within Tuolumne 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.

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.

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 NASA (9), USGS Conterminous (5).

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. Mar 22, 2018Flash Flood$43.0 million
   National Weather Service narrative

   A period of heavy rain upstream from Moccasin Dam, in which about three inches fell during four hours led to significant erosion and at least one landslide. It caused a massive amount of water and debris to run downhill into the Moccasin Reservoir. The water level rose to 3 times the normal reservoir capacity and the emergency spillway was utilized. There was severe erosion of the emergency spillway and potential for the dam to fail. The Power house and staff at the Moccasin Fish Hatchery were evacuated due to potential failure. All the fish in the Moccasin Creek Hatchery were killed when it flooded from the water coming over the emergency spillway. The National Weather Service…

2. Mar 4, 2023Flood$42.0 million
   National Weather Service narrative

   All public entities in Tuolumne County completed a preliminary estimate of storm damage for February through April, with costs well over $42 million.

3. Mar 21, 2018Flood$8.0 million
   National Weather Service narrative

   Extensive flooding in downtown Groveland, as floodwaters ran down the main street, Highway 120. Property was damage and water rescues for stranded residents. There was significant damage done to Groveland Community Hall and Mary Laveroni Community Park. Preliminary estimates from Tuolumne County are approximately $8 million for 16 damaged sites along county maintained roads. A very large portion of these damages are seen in the sinkhole at Ferretti Road and slides and embankment loss on Priest Coulterville Road.

4. Mar 21, 2017Thunderstorm Wind$1.0 million
   National Weather Service narrative

   An NWS storm survey team determined straight line winds from a micro-burst associated with a severe thunderstorm caused damage in Twain Harte, CA Numerous trees were brought down, and a home was damaged. Winds gusted to an estimated 105 mpg. Significant wind damage was done along Twain Harte Rd. with many trees and power lines knocked down as a severe thunderstorm passed through. A woman was briefly trapped in a damaged vehicle by a falling tree, and was rescued by the fire department. The woman was not injured.

5. Jan 19, 2016Thunderstorm Wind$50,000
   National Weather Service narrative

   The main Lake Don Pedro Marina (LDPM) sustained damage to its structure that led to the evacuation of its employees until the weather system died down. The facility was closed for repairs.

6. Mar 11, 2023Thunderstorm Wind$50,000
   National Weather Service narrative

   Tuolumne County OES reported extensive tree damage at Woods Creek Mobile Home Park with 34 trees down.

7. Jun 25, 2020Thunderstorm Wind$50,000
   National Weather Service narrative

   Yosemite National Park dispatch reported several trees donwed in the Hetch Hetchy area due to strong thunderstorm wind gusts.

8. Mar 6, 2014Debris Flow$50,000
   National Weather Service narrative

   The Rim Fire burn scar area received 0.20 to over 1 of rainfall from thunderstorms on the early morning of March 6th. The ground was previously saturated due to rainfall for several days prior to this event. There were approximately 10-11 different debris flow slides along the roadway. The cost of the road repair (removal of slide material, limited necessary reconstruction of road prism and culvert function, and storm proofing) was approximately $50,000 in direct engineering contracting costs. The road had just been rebuilt to new standards prior to the slides. No loss of tree productivity costs because the slopes above and below the road were non-commercial stands.

9. Mar 11, 2023Thunderstorm Wind$30,000
   National Weather Service narrative

   Tuolumne County Emergency Manager reported several trees and power poles down near the intersection of Martin Lane and Campo Seco Road. The Mount Elizabeth RAWS reported a maximum wind gusts of 61 mph.

10. Mar 11, 2023Tornado$20,000
    National Weather Service narrative

    Numerous hardwood trees snapped or uprooted. A wooden power pole snapped in half. NWS Storm Survey determined it to be rated EF-1 with 90 mph winds.

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

113°F2 times, most recently Jul 15, 1972

All-time low

8°F2 times, most recently Dec 10, 1972

Warmest night

79°FAug 8, 1921

Coldest day

33°F2 times, most recently Dec 9, 1972

Wettest day

5.42 inDec 11, 1906

Snowiest day

11.0 inJan 1, 1910

Hottest year

1934mean 62.5°F

Coldest year

1964mean 55.1°F

Wettest year

194046.67 in

Driest year

20139.53 in

Snowiest season

44.0 in1932-33

Station Sonora (USC00048353), 1,675 ft elevation, 3.4 miles from the population centre. Daily records from 1906 to October 27, 2026; 88.4% 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 USC00048353.
• River crests NOAA National Weather Service, National Water Prediction Service river gauges, 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.
• 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.