April in Allentown averages a daily high of 17°C with nights around 4.2°C. Expect roughly 11.8 wet days totalling 97.1mm. Generally workable, with some weather to plan around.
Across the year, the best time to visit Allentown is May–June.
Based on ALLENTOWN LEHIGH VALLEY INTERNATIONAL AIRPORT, PA US (5.8km), 1995–2024. 30 years of April data.