The dataset consists of eleven spreadsheet tabs, each tab containing lipid biomarker palaeothermometry (air temperature reconstructions) and bulk organic carbon isotope data from individual lignites that are known to stratigraphically span the Cretaceous-Palaeogene (K-Pg) boundary. Uncalibrated, raw biomarker distributions (glycerol dialkyl glycerol tetraethers; GDGTs) are provided, as well as the calculated calibration outputs. Site coordinates are: West Bijou, Colorado (39°34'14'N, 104°18'09'W), Sussex, Wyoming (43°39'40"N, 106°19'06"W), Pyramid Butte, North Dakota (46°25'03'N, 103°58'33'W), Hell Creek Road, Montana (47°31'35"N, 106°56'23"W), Rock Creek West, Saskatchewan (49°02'20"N, 106°34'00"W), Wood Mountain Creek, Saskatchewan (49°25'20"N, 106°19'50"W), Frenchman Valley, Saskatchewan (49°20’56"N, 108°25’05"W), Knudesn’s Coulee, Alberta (51°54’27"N, 113°02’57"W) Griffith’s Farm, Alberta (51°54’47"N, 112°57’51"W), Coal Valley Cores (GSC CV-42-2, Cores 1 and 2), Alberta (53°05’02"N, 116°47’ 40"W) Police Island, Northwest Territories (64°52'42"N, 125°12'33"W).