Buenos Aires is best in spring and autumn. The city can get appallingly hot in summer, with temperatures reaching 45C and humidity of at least 80%. It's normally mild in winter, with sunshine.
For information on airlines and airports serving Buenos Aires, see our guide on getting to Argentina.
Buenos Aires has a safe and efficient metro network, called the Subte. The most useful line for tourists is D, which connects Palermo and Recoleta with the city centre. Never hail one from the street.