We have the tenth highest flash flood fatality rate in the nation. Flash floods primarily occur from June through September. Rugged and often steep terrain only sets the stage for rapid storm water runoff across the state. The biggest contributing factor is the summertime increase in thunderstorms capable of producing heavy downpours in short periods of time. Rainfall rates in New Mexico's thunderstorms can, at times, match those of much more humid environments such as southeast Texas and Florida.
People are often surprised at how quickly a normally dry arroyo can become a raging torrent.
Unlike the threat of large hail and tornadoes, found mainly in eastern New Mexico, the risk of flash flooding is highest across central and western portions of the state. After distant heavy rains, arroyos and streams downstream from the actual rain area will carry the storm water runoff for many hours. If you see heavy rain even many miles upstream from your area, remain alert for water in the arroyos and across low water crossings for at least 6 to 12 hours. You can reduce the chances of becoming a flash flood victim by knowing how to recognize these weather hazards as they develop and by observing the following simple safety rules. During periods of thunderstorms, always remain alert to heavy rains in your immediate area or upstream from your location.