| June 2016 | Flash Flood | Duncan | 1 killed | High water rescue due to heavy rain. One foot of water was over US 81 in central part of Duncan. According to police reports, an 8 year old boy (whose body was found 14 days later) tried to cross a bridge at highway 81 and Oak when he went down 10 to 12 feet into rushing water. |
| June 1994 | Thunderstorm Wind | Duncan | $500,000 | no account filed |
| February 2023 | Thunderstorm Wind | Duncan | $80,000 | Widespread wind damage reported throughout Duncan. Numerous houses received damage to their roofs. Additionally, 40 power poles were damaged to varying degrees (broken and/or down) throughout town. |
| April 2024 | Thunderstorm Wind | Duncan | $50,000 | Social media image showing a gas station canopy collapsed due to thunderstorm wind. Time is radar estimated. |
| November 2024 | Tornado (EF1) | Duncan | $50,000 | A mobile home was pushed off it's blocks by a tornado northeast of Duncan. |
| May 1997 | Tornado (F1) | Duncan | $50,000 | A tornado was observed about 3 miles south of Duncan and 1 mile east of Highway 81 by storm spotters. At this location (on "Old Highway 81"), a travel trailer was destroyed, a roof was blown off a large workshop, a brick home was damaged by a falling tree, and a van was damaged. Nearby trees were uprooted, power lines were downed, and a mobile home was destroyed. A puppy that had been inside the damaged mobile home was found 1/4 mile north of the house in someone else's yard. In the same area, 8 empty grain train cars were blown over off a side track. |
| May 2003 | Tornado (F1) | Duncan | $35,000 | This tornado moved north-northeast between Highway 7 and Old Highway 7. Three houses sustained roof damage. The tornado also heavily damaged 5 barns in this area. A pickup and camper sustained major damage. Power lines, fences, and numerous trees were also downed. |
| May 1999 | Thunderstorm Wind | Duncan | $35,000 | no account filed |
| March 2004 | Thunderstorm Wind | Duncan | $20,000 | A barn was destroyed at the corner of 42nd and Fuller Streets. |
| July 2006 | Dust Devil | Duncan | $15,000 | An eyewitness observed a dust devil, approximately 50 feet in diameter, rip the roof off of the Oklahoma State University Extension Service Office building at the Stephens County Fairgrounds. The dust devil then moved off a short distance, with the edge affecting a line of parked cars. The witness observed the cars significantly rocking and for a short time thought a few might tip over. However, no cars did turn over. |
| November 2024 | Thunderstorm Wind | Duncan | $10,000 | An image relayed by the Oklahoma Department of Emergency Management shows the metal facade of an old masonry building blown off. Event time is radar-estimated. |
| May 2007 | Flash Flood | Duncan | $10,000 | Portions of HWY 81 were closed due to water up to 18 inches deep. Several cars were washed off the roadway near the Chisholm Trail Mall. Monetary damages were estimated. |
| May 2001 | Flash Flood | Duncan | $10,000 | A residence was flooded in the 1300 block of Chestnut St. |
| May 1997 | Lightning | Duncan | $10,000 | Lightning struck and set fire to a mobile home |
| October 2016 | Thunderstorm Wind | Duncan | $5,000 | Wind knocked down an 8 inch branch onto a house with a metal roof that caused one section of the roof to crash in the house. |
| May 2015 | Thunderstorm Wind | Duncan | $5,000 | Several large trees and tree limbs downed. |
| June 2004 | Thunderstorm Wind | Duncan | $5,000 | Power lines were downed on Highway 7. |
| August 2004 | Thunderstorm Wind | Duncan | $5,000 | Power lines were downed near the junction of State Highway 7 and US Highway 81. |
| May 2003 | Thunderstorm Wind | Duncan | $5,000 | Utility poles were reported downed for three miles. |
| August 1997 | Thunderstorm Wind | Duncan | $5,000 | Severe thunderstorm winds blew the roof off a barn and carried it over a house and onto a road. The roof of the house was severely damaged. Winds also uprooted trees and snapped limbs. |
| May 2000 | Thunderstorm Wind | Duncan | $4,000 | Six large trees were downed along Highway 81 at Fuqua Park. |
| December 2022 | Tornado (EF1) | Duncan | $3,000 | A large tree was uprooted and a power pole snapped as a tornado touched down in the northwest part of Duncan. At the same time, the rear-flank downdraft from the storm was producing damage across southwest and central portions of Duncan. |
| June 1999 | Lightning | Duncan | $3,000 | no account filed |
| April 2016 | Thunderstorm Wind | Duncan | $2,000 | Power lines downed along with numerous tree limbs and a blown over fence. Power outages were also reported in Duncan. |
| November 1998 | Thunderstorm Wind | Duncan | $2,000 | no account filed |
| August 2005 | Thunderstorm Wind | Duncan | $1,000 | Power poles and tree limbs were downed. |
| March 2004 | Thunderstorm Wind | Duncan | $1,000 | Several seven inch diameter trees were downed. |
| July 2004 | Thunderstorm Wind | Duncan | $1,000 | Power lines were downed on north side of town. |
| July 2004 | Thunderstorm Wind | Duncan | $1,000 | Power lines were downed. |
| June 1997 | Thunderstorm Wind | Duncan | $1,000 | A carport was destroyed and windows were broken out of a residence in southeast Duncan. |
| May 1999 | Thunderstorm Wind | Duncan | $1,000 | no account filed |
| April 2016 | Thunderstorm Wind | Duncan | $500 | Power poles down. |
| June 2006 | Thunderstorm Wind | Duncan | $500 | A large tree was downed blocking Highway 81. |
| October 2002 | Thunderstorm Wind | Duncan | $500 | Trees were downed. |
| May 2001 | Thunderstorm Wind | Duncan | $500 | Power lines were downed. |
| May 2000 | Thunderstorm Wind | Duncan | $500 | Trees were downed on a refinery road. |
| August 1999 | Thunderstorm Wind | Duncan | $500 | no account filed |
| August 1999 | Thunderstorm Wind | Duncan | $500 | no account filed |
| August 1999 | Thunderstorm Wind | Duncan | $500 | no account filed |
| August 1998 | Lightning | Duncan | $500 | no account filed |
| May 1996 | Thunderstorm Wind | Duncan | $500 | no account filed |
| May 1999 | Thunderstorm Wind | Duncan | $100 | no account filed |
| June 2003 | Thunderstorm Wind | Duncan | $70 | A four inch diameter tree was downed near the intersection of 11th Street and Woodlawn. |
| June 2002 | Thunderstorm Wind | Duncan | $10 | Large tree limbs were downed. |
| March 2026 | Hail | Duncan | - | The report was relayed through mPING. The event time is adjusted based on radar observations. |
| April 2026 | Hail | Duncan | - | The report was relayed through mPING. |
| March 2025 | Hail | Duncan | - | MPing report. |
| March 2025 | Hail | Duncan | - | Relayed image. Event time is estimated from radar observations. |
| March 2025 | Hail | Duncan | - | Relayed images with ruler measurement. |
| May 2025 | Hail | Duncan | - | The report was relayed through mPING. The event time is adjusted based on radar observations. |
| May 2025 | Flood | Duncan | - | Roadway flooding occurred along portions of U.S. Highway 81, just north of the community of Duncan. The event time is approximate. |
| April 2025 | Hail | Duncan | - | A social media image. |
| April 2025 | Hail | Duncan | - | The report was relayed through mPING. |
| April 2025 | Hail | Duncan | - | The report was relayed through mPING. |
| April 2025 | Hail | Duncan | - | The report was relayed through mPING. |
| April 2025 | Flash Flood | Duncan | - | Roadway flooding and multiple water rescues just south of the community of Duncan, most notably along Seminole Road and near the intersection of Cherokee Road and Oklahoma Highway 7. Event time is approximate. |
| April 2025 | Flash Flood | Duncan | - | Multiple confirmations of roadway flooding in and around the community of Duncan, especially along U.S. Highway 81 near Clarity Creek. Multiple water rescues were reported. Event time is approximate. |
| April 2024 | Flash Flood | Duncan | - | Heavy rainfall caused Claridy Creek to rise out of its banks, flooding a portion of U.S. Highway 81 near the Elder Avenue intersection. Event time is approximate. |
| April 2024 | Hail | Duncan | - | MPing report. |
| April 2024 | Hail | Duncan | - | MPing report. Time is radar estimated. |