There are many Airlines that Flight directly to and from Mexico City: https://www.aicm.com.mx/en/flights/airlines
From Airport to the Hotel Ritz (Centro Histórico) a regular taxi rate is in the U$S 12-15 range (around MXN $250 MXN). We recommend that you buy a "ticket" for a taxi inside the airport, for which you can specify your destination and pay with a credit card.
There are many money exchange stores at the airport. You can also find ATM machines just in front of the last exit door after passing customs. ATM machines are available all around the city. Credit cards are widely accepted.
Information about flights or facilities inside the airport: https://www.aicm.com.mx/en/
More info (in Spanish): https://www.aeropuertos.net/aeropuerto-internacional-de-la-ciudad-de-mexico/
Weather during the event
Weather is never a subject of conversation in Mexico but, in the case you are curious, AccuWeather provides you the historic averages: 19.5/7 Celsius, 67/45 Farenheit.
More useful information to prepare your trip
Mexico and its food
One of the world’s largest cities, Mexico City offers a wide variety of attractions, activities and experiences for all visitors to its vast expanse.
Our country is the result of the ancient Mexican culture, enriched by the wisdom of pre-Hispanic populations and the novelties that different foreign migrations have brought.
Therefore, since 2010, traditional Mexican cuisine is part of the Intangible Cultural Heritage of United Nations Educational, Scientific and Cultural Organization (UNESCO) in accordance with the resolution approved by the corresponding Intergovernmental Commission at its session in Nairobi, Kenya.
What to do?
Mexico City is a destination with an extraordinary mysticism that revels in its overlapping plurality, folklore, and modernity; everything here is an intermixture, its pre-Hispanic roots present in its foundations, as shown by the Metropolitan Cathedral that sits on top of the pyramid of Tonatiuh.
Visit of the HAWC experiment
If you have more time (at least 3 days more) and you are healthy enough you can visit the HAWC experiment site located at Sierra Negra (4200 mamsl) in the limits of the states of Puebla and Veracruz (ask Jesús Martinez in Advance as it is a 6 hrs trip).