The altitude in Mexico City is 7200 feet. As a result, the weather is mild and dry. Okay, in December, when I visited, it was perfect.
Highs of about 74 during the day, and lows of 45 at night. Sunny, cloudless skies. (I returned home to 18 degrees in Chicago, and the beginning of our annual 4 months of gray).
Our IPA Congress will be held during the city’s rainy season. I am told that in August temperature highs during the day will be about 80. There will be a downpour around 5 pm every single day and it will last about an hour. Then the skies will clear and there will be a cool comfortable night. A sweater or light jacket is advised.
Dress is what we in the states might call “business casual” or “dressy casual”. But obviously people wear city clothes, not beachwear. Men do not often wear suit jackets (unless they are politicians) and ties are optional.