Kaohsiung has a hot tropical climate — much warmer than Taipei, and noticeably drier.
October to March is the best time to visit, with daytime temperatures of 22-28°C and little rain. December and January can feel cool to locals but are pleasant for walking.
April to June is hot (28-32°C) and humid, with afternoon thunderstorms common from May. Still pleasant if you can deal with the heat.
July to September is the height of summer and typhoon season. Daily highs above 33°C, oppressive humidity, and the occasional typhoon shutting things down for a day or two. Avoid if you are not used to heat.
The Kaohsiung Lantern Festival on the Love River around Lunar New Year (late January or February) is the city's signature event, with thousands of lanterns floated on the water. The Spring Scream music festival down in Kenting draws crowds away in April; the city itself is quieter then.