We plan go Taipei last week of Sept for 4days vacation & I want to know if weather is still hot...

...or is it chilly already? September is still part of SUMMER SEASON months but since we plan go last week of September maybe the weather is starting to get cold already. Would it be better if we go there the 1st week of October instead of last week of September because we want to avoid HOT WEATHER in Taiwan? Does the weather changes greatly in a span of one week time only? Thank you