The pilot reported that the agricultural airplane was on takeoff roll when a sudden wind gust caused the airplane to swerve left. He was unable to regain directional control of the airplane before it departed the left side of the runway, through a drainage ditch, and into a cornfield. The airplane sustained substantial damage to both wings, aft fuselage, empennage, and the engine mounts. The pilot did not report any mechanical malfunctions with the airplane that would have precluded normal operation. Earlier in the day, the pilot had reviewed the local forecast on the National Weather Service website, which stated that there was a chance of thunderstorms later in the afternoon. He also reviewed the weather conditions periodically throughout the day using a weather application on his mobile phone/tablet, but the last time he had reviewed the weather application was about 15 minutes before the accident, at which time he did not observe any thunderstorms in the local area. The pilot did not review any weather data before the accident flight. According to weather radar data, a significant thunderstorm was approaching the airstrip from the southwest in the minutes preceding the accident and was over the airstrip about 5 minutes after the accident. The pilot’s inability to maintain directional control during the takeoff was likely due to a sudden change in wind direction and speed associated with the approaching thunderstorm.