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. If you need a taxi, always phone for a radio taxi (never hail one off the street).