Monday's 105 degree temperature was a tie for the hottest day in Denver, ever. Two previous days where that hot: August 8, 1878 and July 20, 2005. Various other heat records are being set left and right.
UPDATE: 105 degrees again today (June 26, 2012), the first time in Denver history that there have been two 105 degree days in a row and a tie for the record number of 100 degree plus days in the row in Denver (five tied in 1989 and 2005). The forecast high for tomorrow is 93 degrees so a record breaking six day streak of 100 degree plus days seems unlikely. There is also a real possibility that average temperatures this June will be the hottest on record.