INTRODUCTION Recent efforts within the National Weather Services Southern Region (NWS-SR) to refine criteria for excessive heat revealed high occurrences of extreme temperatures in the upper Red River Valley of southwestern Oklahoma and northwestern Texas. Recent efforts within the National Weather Services Southern Region (NWS-SR) to refine criteria for excessive heat revealed high occurrences of extreme temperatures in the upper Red River Valley of southwestern Oklahoma and northwestern Texas. Between 2000 and 2014, several observing sites within the area recorded more than 200 instances of daily maximum temperatures 40 C (105 F) with temperatures 43 C (110 F) occurring on average two to three times per year. Between 2000 and 2014, several observing sites within the area recorded more than 200 instances of daily maximum temperatures 40 C (105 F) with temperatures 43 C (110 F) occurring on average two to three times per year. This represents a 300% increase in the occurrence of temperatures 40 C (105 F) and a three- to eight-fold increase in the frequency of 43 C (110 F) temperatures relative to the remainder of the southern Great Plains for the fifteen-year period. This represents a 300% increase in the occurrence of temperatures 40 C (105 F) and a three- to eight-fold increase in the frequency of 43 C (110 F) temperatures relative to the remainder of the southern Great Plains for the fifteen-year period. This study reviews heat wave episodes in the upper Red River Valley of Oklahoma and Texas. The North American Regional Reanalysis (NARR) is used to identify and quantify mean synoptic-scale atmospheric patterns associated with forty multi- day heat waves between 2000 and This study reviews heat wave episodes in the upper Red River Valley of Oklahoma and Texas. The North American Regional Reanalysis (NARR) is used to identify and quantify mean synoptic-scale atmospheric patterns associated with forty multi- day heat waves between 2000 and Lastly, climatological evidence is examined to determine if the frequency of heat waves in the upper Red River Valley has increased during the recent southern Great Plains drought. Lastly, climatological evidence is examined to determine if the frequency of heat waves in the upper Red River Valley has increased during the recent southern Great Plains drought. SUMMARY Meteorological composites were generated using the NARR for forty multi-day heat waves that occurred in the upper Red River Valley of the southern Great Plains between Composites showed 5925 m 500 hPa geopotential heights, a 1006 hPa MSLP trough (thermal low), and relative humidity