September in Portsmouth averages a daily high of 27°C with nights around 18.5°C. Expect roughly 9.2 wet days totalling 154.4mm. Comfortable conditions for being outdoors all day.
Across the year, the best time to visit Portsmouth is April–May.
Based on NORFOLK SOUTH, VA US (7.3km), 1995–2024. 22 years of September data.