This study aimed to investigate the synoptic patterns contributing to the formation of heat waves during the cold season in Ardabil Province over a 41-year period (1980–2020). Daily maximum temperature data from the synoptic stations of Ardabil, Parsabad, and Meshginshahr were collected. Heat waves were defined based on the 95th percentile threshold, as periods of at least three consecutive days with daily maximum temperatures exceeding the respective monthly threshold. To analyze the associated atmospheric conditions, sea level pressure and 500 hPa geopotential height data from the NCEP/NCAR reanalysis were employed, and dominant patterns were identified using Ward’s hierarchical clustering method. The results indicated that the highest thermal thresholds (95th percentile) at all three stations occurred in April. During the study period, the total number of heat waves at Ardabil, Meshginshahr, and Parsabad stations was 39, 26, and 20, respectively. Ardabil experienced the highest frequency, whereas Meshginshahr recorded the longest duration of heat waves. Cluster analysis revealed two dominant synoptic patterns associated with persistent heat waves (≥5 days): Pattern I (example: 15 March 2010): The presence of a surface anticyclone combined with a mid-tropospheric ridge induced subsidence and adiabatic warming. Pattern II (example:10 December 1998): The development of a broad surface anticyclone and the positioning of the region ahead of a deep trough at 500 hPa facilitated the advection of warm air from southern and southwestern latitudes into the province. In both patterns, the clockwise circulation of anticyclonic systems enhanced the transport of warm air masses from lower latitudes toward Ardabil.