Prescribed fire is a common management tool in grasslands but the efficacy and safety of prescribed burns are closely linked to weather conditions, which are expected to change under global climate change. While much is understood about grassland prescribed fire seasons for the central and southern plains, there has been relatively little investigation into prescribed fire conditions within the Northern Plains. This region has been experiencing the most rapid climate change in the lower 48 states. We investigated the impact of climate change on grassland prescribed fire seasons in the Northern Plains. We collected data from Remote Automated Weather Stations (RAWS) within the Grand Forks (n = 12; GFFWZ) and Bismarck (n = 13; BIFWZ) North Dakota National Weather Service Fire Weather Zones and related these data to records of regional fires (both wildfires and prescribed fires; n = 1484) to ask how acceptable conditions and fire danger indices associated with spring and fall fire seasons have changed over the last 13 years (2002 – 2015).
Results/Conclusions
Within the region, days with fire danger indices exceeding recommendations for prescribed fire management (e.g. > 30 Burning Index) are more frequent prior to spring green-up than in the fall. Within the GFFWZ, the number of > 30 Burning Index days has remained stable over the past 13 years. Recorded fires (included prescribed and wildfires) occurred more frequently than expected during periods of low relative humidity (median RH = 45%), low fuel moisture (median = 8%) and low Burning Index (median = 7), likely reflecting a propensity for citizens and managers to conduct operations under these conditions. Surprisingly, fire occurrences were not any more or less frequent under varying wind speed conditions (median = 8 mph), indicating this is a not good measure of regional fire activity. Results indicate that more opportunity exists for consistent application of prescribed fire management within the fall fire season and that fire is used under a greater range of conditions than previously documented.