Sierra County

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.

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 CA GS (1).

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 18, 2021High Wind, Central Sierra$200 million
   National Weather Service narrative

   Estimated 100 mph gusts near Yosemite Valley toppled several trees knocking out power to nearly all of Yosemite Park for several days. In addition, several structures were damaged by the winds and the park was closed for several days. The repairs required for Yosemite National Park from this wind event are exepcted to exceed $200 million.

2. Feb 9, 2017Flood$6.8 million
   National Weather Service narrative

   Flooding from creeks covered the intersection of Highways 49 and 89 in Sierraville on the afternoon of the 9th. Shallow water was photographed up against buildings at the Sierraville Ranger Station on the morning of the 10th. A washout caused the closure of Highway 49 between Sattley and Yuba Pass. Damage estimates are only for repairs to Highways 49 and 89 based on a CALTRANS report.

3. Jan 11, 2017Debris Flow$1.6 million
   National Weather Service narrative

   State Route 49 in Sierra County closed due to a rock/mud slide blocking the roadway. The guard rail was damaged.

4. Dec 30, 2005Flood$1.0 million
   National Weather Service narrative

   Debris in streams caused water to back up and caused flooding in portions of eastern Sierra County. Several buildings experienced flooding, including the U.S. Forest Service office in Sierraville. California Highway 89 was closed across Sierra County from the Nevada County line to Calpine.

5. Dec 14, 2002High Wind, Lassen/Eastern Plumas/Eastern Sierra$220,000
   National Weather Service narrative

   A strong cold front moving through northern California on December 14 brought near-record nigh winds to northeast California and western Nevada. Wind gusts reports in the 60-80 mph range were common throughout the day across the entire region, with a few gusts near 100 mph. Remote wind sensors along the Sierra Crest measured wind gusts in excess of 130 mph. Strongest winds occurred just before the cold front moved into the area at about 5:30 p.m. Literally hundreds of trees and thousands of tree limbs were blown down across the region. In addition, there was widespread damage to roofs, fences, commercial billboards and signs, and power lines. Numerous power outages occurred, some…

6. Dec 14, 2002High Wind, Lassen/Eastern Plumas/Eastern Sierra$220,000
   National Weather Service narrative

   A strong cold front moving through northern California on December 14 brought near-record nigh winds to northeast California and western Nevada. Wind gusts reports in the 60-80 mph range were common throughout the day across the entire region, with a few gusts near 100 mph. Remote wind sensors along the Sierra Crest measured wind gusts in excess of 130 mph. Strongest winds occurred just before the cold front moved into the area at about 5:30 p.m. Literally hundreds of trees and thousands of tree limbs were blown down across the region. In addition, there was widespread damage to roofs, fences, commercial billboards and signs, and power lines. Numerous power outages occurred, some…

7. Dec 14, 2002High Wind, Lassen/Eastern Plumas/Eastern Sierra$220,000
   National Weather Service narrative

   A strong cold front moving through northern California on December 14 brought near-record nigh winds to northeast California and western Nevada. Wind gusts reports in the 60-80 mph range were common throughout the day across the entire region, with a few gusts near 100 mph. Remote wind sensors along the Sierra Crest measured wind gusts in excess of 130 mph. Strongest winds occurred just before the cold front moved into the area at about 5:30 p.m. Literally hundreds of trees and thousands of tree limbs were blown down across the region. In addition, there was widespread damage to roofs, fences, commercial billboards and signs, and power lines. Numerous power outages occurred, some…

8. Dec 14, 2002High Wind, Lassen/Eastern Plumas/Eastern Sierra$220,000
   National Weather Service narrative

   A strong cold front moving through northern California on December 14 brought near-record nigh winds to northeast California and western Nevada. Wind gusts reports in the 60-80 mph range were common throughout the day across the entire region, with a few gusts near 100 mph. Remote wind sensors along the Sierra Crest measured wind gusts in excess of 130 mph. Strongest winds occurred just before the cold front moved into the area at about 5:30 p.m. Literally hundreds of trees and thousands of tree limbs were blown down across the region. In addition, there was widespread damage to roofs, fences, commercial billboards and signs, and power lines. Numerous power outages occurred, some…

9. Dec 14, 2002High Wind, Lassen/Eastern Plumas/Eastern Sierra$220,000
   National Weather Service narrative

   A strong cold front moving through northern California on December 14 brought near-record nigh winds to northeast California and western Nevada. Wind gusts reports in the 60-80 mph range were common throughout the day across the entire region, with a few gusts near 100 mph. Remote wind sensors along the Sierra Crest measured wind gusts in excess of 130 mph. Strongest winds occurred just before the cold front moved into the area at about 5:30 p.m. Literally hundreds of trees and thousands of tree limbs were blown down across the region. In addition, there was widespread damage to roofs, fences, commercial billboards and signs, and power lines. Numerous power outages occurred, some…

10. Dec 14, 2002High Wind, Lassen/Eastern Plumas/Eastern Sierra$220,000
    National Weather Service narrative

    A strong cold front moving through northern California on December 14 brought near-record nigh winds to northeast California and western Nevada. Wind gusts reports in the 60-80 mph range were common throughout the day across the entire region, with a few gusts near 100 mph. Remote wind sensors along the Sierra Crest measured wind gusts in excess of 130 mph. Strongest winds occurred just before the cold front moved into the area at about 5:30 p.m. Literally hundreds of trees and thousands of tree limbs were blown down across the region. In addition, there was widespread damage to roofs, fences, commercial billboards and signs, and power lines. Numerous power outages occurred, some…

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

110°F2 times, most recently Jul 1, 1924

All-time low

−28°FDec 9, 1972

Warmest night

75°FJul 21, 1916

Coldest day

4°F2 times, most recently Dec 22, 1990

Wettest day

5.67 inOct 25, 2021

Snowiest day

40.2 inDec 25, 1971

Hottest year

2021mean 49.6°F

Coldest year

1922mean 40.6°F

Wettest year

201743.92 in

Driest year

20136.56 in

Snowiest season

222.5 in2022-23

Station Portola (USC00047085), 4,850 ft elevation, 13.9 miles from the population centre. Daily records from 1915 to October 26, 2026; 91.1% 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 USC00047085.
• 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.