"Station: Allentown INTL AP, PA". U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991–2020). National Oceanic and Atmospheric Administration. Retrieved August 8, 2021.
Official records for Allentown were kept at Allentown Gas Company from March 1922 to December 1943, and at Lehigh Valley Int'l since January 1944. For more information, see ThreadEx.