Here are the cities that have good weather in a specific month:
January
February
March
April
May
June
July
August
September
October
November
December
Cities with great weather in September
Ho Chi Minh City in January Good
Puerto Vallarta in January Good
Ho Chi Minh City in February Great
Puerto Vallarta in February Good
Puerto Vallarta in November Good
Ho Chi Minh City in December Good
Puerto Vallarta in December Good