Subtropical and humid, with loads of sun and only about 50in of rain a year. The vicious summers are made more intolerable by the lack of a breeze. When the wind does come you'll know about it; Houston is no stranger to tropical storms and hurricanes. Winters are cool and temperate.
Houston has two airports: George Bush Intercontinental Airport (IAH) is served by major domestic and international airlines with two interterminal train systems connect passengers to all five terminals; William P Hobby Airport (HOU) is a main hub for Southwest Airlines and domestic travel.
Limited bus service is available to Bush Intercontinental Airport, making taxis and private shuttle buses a better bet. Bus service to Hobby Airport is more reliable. The Airport Direct bus runs between downtown and Bush Intercontinental throughout the day. Whereas SuperShuttle provides service from both Bush and Hobby airports. Both airports have car rental agencies.
Houston's Metropolitan Transit Authority runs the convenient light-rail system. Most of the in-town sights are along the Downtown-Museum District- Reliant Park light-rail corridor. If you want to venture further, you'll need to rent a car; the bus system is mostly inefficient for visitors' needs.
By far the best way to get around Houston is with a car. Museum District sights are clustered together so you can ditch your wheels and walk around a bit. Other sights and attractions are far enough that driving is the only convenient way to reach them. Driving is on the right. Every major national car-rental agency can be found at either airport.
As a city built around the car, Houston has highways radiating in all directions.
Greyhound is the major bus carrier, with a web of services in all directions. Long-distance buses arrive at the Greyhound Bus Terminal, which is located between downtown and the Museum District, and two blocks from the Downtown Transit Center light-rail stop.
The Sunset Limited train stops at the Amtrak Station (902 Washington Ave) three times a week.
All US visa information is highly subject to change. US entry requirements keep evolving as national security regulations change. All travelers should double-check current visa and passport regulations before coming to the USA. The US State Department maintains the most comprehensive visa information, providing downloadable forms, lists of US consulates abroad and even visa wait times calculated by country.
Health and Safety
Don't worry if everyone seems to stay indoors in this town - they're more than likely escaping the mosquitos and the heat rather than each other. Houstonites are a particularly friendly bunch and will be more than happy to steer you away from any trouble spots. Areas to the east and southeast of downtown Houston can be sketchy at any time, but that description is by no means universal. Other than dangerous drivers, heat is probably the biggest danger. Summer temperatures over 100°F coupled with extreme humidity can exhaust a hardened cowboy: drink water and seek shade. As in any city, take precaution, lock your car and take valuables with you.