Denison

Every recorded tornado

1. Injuries and deaths are for the tornado’s whole path, which may extend beyond this area.
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 storm within 100 miles

1. Tropical storms and hurricanes (34 kt or more, still tropical) at closest approach. Post-tropical remnants with gale-force winds are listed but not counted. Direct: track within 50 miles; near: within 100 miles. Distance is measured to the county boundary for counties and to the city centre for cities, using positions interpolated hourly between HURDAT2 fixes.

National Hurricane Center HURDAT2, 1851 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.

Flood insurance figures are for Grayson County, the county that contains Denison.

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.

The drought index is for Grayson County, the county that contains Denison.

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.

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 city centre.
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.

More event types since 1996

Costliest events since 1996

1. Jun 18, 2007Flash Flood$20.0 million
   National Weather Service narrative

   Significant flooding occurred with cars and mobile homes moved by the force of the water. Numerous roads were closed across the county, including Highways 377 and 75, and more than 450 people were rescued from high water. One woman died in floodwaters as she drove on Texoma Parkway under the U.S. Highway 75 overpass. Another fatality occurred when a truck flooded at the intersection of FM 1417 and Highway 11. A bridge on Highway 11 south of Sherman suffered extensive damage.

2. Apr 6, 2003Hail$10.0 million
   National Weather Service narrative

   Hail up to baseball size did extensive damage in Sherman to cars and houses. This is the same storm that hit the Whitesboro area earlier.

3. Dec 5, 2013Winter Storm, Grayson$7.0 million
   National Weather Service narrative

   Up to 4 of ice and sleet accumulated in Grayson County. On average, 3-4 of ice and sleet was reported and most of the reports were sleet accumulations. One media station in Denison reported 0.10 ice with 3 of sleet accumulations. Traffic became very difficult, including Highway 82 and Highway 289. Several traffic accidents occurred on the icy streets and hundreds of tree branches broke due to the weight of the ice. Due to the weight of the ice, the Lonestar Lanes Bowling Alley in Sherman collapsed on the 6th and the gymnasium roof at the Boys and Girls Club in Sherman also caved in. The roof of the Cooper-B building sagged inward due to the ice. In Denison, an awning collapsed at…

4. Feb 14, 2021Extreme Cold/Wind Chill, Grayson$3.8 million
   National Weather Service narrative

   Extreme cold gripped the county for several days. Overnight lows were near or below 10 degrees Fahrenheit almost all week. The period of February 15-16th was the coldest with low temperatures between 2 and -5 degrees Fahrenheit, and the maximum temperature on the 15th was only in the lower teens. Wind chill values during the 14th-16th were between 0 to -20 degrees Fahrenheit most of the time. The cold temperatures resulted in an extreme amount of damage to pipes, infrastructure, and power.

5. Apr 29, 2009Flood$2.0 million
   National Weather Service narrative

   Widepsread flooding continued through the night across the county with several roads and bridges under water and several areas inaccessible.

6. Sep 8, 2010Flash Flood$750,000
   National Weather Service narrative

   Numerous roads throughout the county were closed due to high water, especially in the southwestern portions of the county. Water rescues were conducted in the cities of Sherman and Gunter. One house was flooded in the city of Denison.

7. Dec 8, 2008Tornado$750,000
   National Weather Service narrative

   According to a damage survey conducted by the National Weather Service in Fort Worth, a lower EF-2 tornado affected areas of south and southwest Denison. Trees and power lines were downed. Dozens of homes, storage shelters, and businesses were damaged. About 500 homes in the area were without power.

8. May 9, 2006Tornado$500,000
   National Weather Service narrative

   A significant tornado which formed in northern Collin County continued into southeastern Grayson County. A damage survey conducted by the National Weather Service in Fort Worth found that the tornado remained strong F3 as it crossed into Grayson County. A fatality occurred on Black Road, just over the border into Grayson County, where permanent homes suffered heavy damage. Numerous trees were snapped or uprooted along Yellow Bridge Road, Durham Road, and Red Moore Road. The tornado damaged outbuildings, rolled over a mobile home, and caused at least minor damage to structures in the area. The tornado, which had briefly weakened to an F1, strengthened again and caused F2 damage as…

9. Oct 1, 2006Drought, Grayson$500,000
   National Weather Service narrative

   Persistent drought conditions continued across portions of north Texas. According to the U.S. Drought Monitor, much of the region was still experiencing extreme (D3) drought conditions. The areas which were rated exceptional drought (D4) last month had received enough rainfall to be downgraded into the D3 category this month.|Even though drought conditions were lessened by a few rain events this month, serious hydrological problems remained. For instance, as much water was used from Lake Bridgeport in one month alone as was saved through conservation efforts by north Texas over the summer. Almost every north Texas lake remained well below conservation levels. The rain events this…

10. Apr 26, 2016Tornado$450,000
    National Weather Service narrative

    A National Weather Service damage survey team determined a tornado produced EF-0 and EF-1 damage to several homes, businesses, and one school on the evening of April 26th. The tornado occurred in Howe, just south of the Sherman city limits, beginning on the west side of US 75. The tornado damaged a mobile home business near the Howe High School, where superficial damage was done due to debris flying into and onto the school. The damage to the school was mainly superficial, however. The tornado continued to move northeast and damaged approximately 20 homes, causing widespread roof, fence, and vehicle damage. Five people were injured in this area, but none had life threatening injuries.

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°FAug 10, 1936

All-time low

−3°FFeb 16, 2021

Warmest night

87°F2 times, most recently Aug 1, 1904

Coldest day

9°FFeb 15, 2021

Wettest day

8.40 inAug 28, 1920

Snowiest day

7.0 inJan 16, 1964

Hottest year

1921mean 68.0°F

Coldest year

1983mean 60.7°F

Wettest year

201577.40 in

Driest year

196318.63 in

Station Sherman (USC00418274), 760 ft elevation, 5.6 miles from the city centre. Daily records from 1897 to October 26, 2026; 96.8% 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.

Declarations for Grayson County.

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.

• 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 USC00418274.
• 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.
• 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.