Maps of the systems are available at their respective websites. Passes are required for the use of BART trains, and can be purchased from machines at any BART station. Some BART stations do not have machines that yet accept the newest currency. MUNI and BART are separate systems. Passes are not interchangeable between the two, even though they share some underground stations.
Cable cars have a unique fare structure and rules.
Please link to Cable Cars for the most current information. The temperature is usually very mild, it is rare if it ever drops below 45 or goes above 90. As a result, any humidity is practically unnoticeable. In summer it can actually feel chilly on occasion, due to weather patterns on the coast. Fog can often be seen around the bay and in the higher elevations of The City.