Heavy snow or blizzards can make landing and taking off too dangerous, while lightning storms can be very hazardous to any aircraft. Extreme heat can also interfere with an aircraft's performance, so in hotter parts of the world, extreme temperatures can cause significant delays.

Aviation is designed to handle a wide range of conditions, but certain weather phenomena are strictly prohibitive for safety. Thunderstorms are the most significant threat, as they contain extreme turbulence, updrafts, and downpours that can lead to engine flameouts or structural damage. While planes can fly through rain, they will not take off or land in severe wind shear (sudden changes in wind speed or direction), which can cause a dangerous loss of lift near the ground. Icing is another critical factor; if a plane’s anti-icing systems cannot keep up with freezing rain or heavy sleet, the ice changes the shape of the wing, destroying the aerodynamics necessary for flight. Heavy fog that reduces visibility below "Category III" minimums will grounded most flights, as pilots must be able to see the runway or rely on sophisticated automated landing systems. High heat is also a factor; when temperatures exceed roughly 118°F (48°C), the air becomes too thin for some smaller jets to generate enough lift to take off safely. Ultimately, the decision to ground a flight rests on the "Minimums" set by the FAA and the specific safety limits of the aircraft.