So atmospheric pushback isn't just a problem for deep-space missions. Even crafts that were built to orbit the Earth and go no further have to deal with this issue.
One such object is the International Space Station (ISS). A crewed laboratory, the ISS orbits roughly 220 miles (350 kilometers) above Earth, completing about 16 revolutions around the planet every day.
NASA used to send astronauts up to the ISS in reusable Space Shuttles. Every day, the ISS would pass over (or near) the launching site at Cape Canaveral. For a successful rendezvous to occur, NASA's shuttles needed to take off within five minutes of that passage. And to avoid dumping fuel tanks onto populated areas, the ships had to follow a south-to-north trajectory over the Atlantic Ocean.
You won't see any of those launches on NASA's 2019 schedule. The American space shuttle program was retired in 2011 and NASA no longer ferries astronauts to the ISS. (At the moment, that's Russia's job.)
Regardless, the Kennedy Space Center sees off loads of other missions every year. By the way, NASA's got plenty of other launch sites at its disposal, including the Vandenberg Air Force Base in southern California.
Wherever a launch is scheduled to begin, you can bet that NASA meteorologists are paying close attention to the weather. Early in 2019, the much-anticipated liftoff of a SpaceX Falcon Heavy Rocket at Cape Canaveral was delayed due to high winds. Back in 1971, "weather constraints" forced NASA to postpone the Apollo 14 launch by 40 minutes.
Rain, lightning and wind aren't the only things that could potentially interfere with a launch. To avoid putting any passing airplanes in harm's way, NASA collaborates with the U.S. Air Force and Federal Aviation Administration to close large swaths of commercial airspace during launch windows.