The 1-hr Dead Fuel Moisture map displays the % moisture content on a dry-weight basis of 1-hour dead fuels as calculated by a calibrated version of the Nelson dead fuel moisture model. Calculated values can range from 1% to 85%. One-hour fuels are the fine dead fuels (< 0.25”) such as grasses which are often involved in the initiation and maintenance of wildland fires and whose moisture contents respond quickly (within minutes) to changing weather conditions. These dead fuels include herbaceous plants, roundwood, and also the uppermost layer of litter on the forest floor. For prescribed fire, the preferred range of 1-hour dead fuel moisture is from 7 to 20%. Below 7%, spot fires become a problem and above 20% there will be problems in starting and maintaining the fire due to too much moisture in the fine fuels. To understand the influence of 1-hour dead fuel moisture on prescribed burning and wildfire, consult OK-FIRE Basics for Prescribed Burning and OK-FIRE Basics for Fire Danger.