Commit to Launch: Contingency Landing Criteria
Weather criteria for a landing also pertain to a launch since the possibility exists for a Return To Launch Site Abort (RTLS) or for an emergency landing at an off-site location.

The following weather criteria pertain to the KSC Shuttle Landing Facility, the Trans-Atlantic Abort Sites (TAL), the Abort Once Around (AOA) sites of Edwards Air Force Base, and White Sands Space Harbor:

Cloud coverage less than 5 tenths below 8,000 feet with a clear line of sight to the end of the runway.

No detached opaque thunderstorm anvil cloud within 10 nautical miles of the runway or within 5 nautical miles of the final approach path extending to 30 nautical miles distance.

For RTLS and the TAL sites, no thunderstorms, lightning, or precipitation within 20 nautical miles of the runway, or within 10 nautical miles of the approach path extending to 30 nautical miles distance.

Visibility for RTLS, 7 statute miles or greater

Visibility for the TAL sites and AOA, 5 statute miles or greater where microwave landing system (MLS) instrument landing capability is available; otherwise 7 statute miles.

Crosswind component for Return To Launch Site (RTLS) not to exceed 15 knots. For Abort Once Around (AOA) and Trans-Atlantic (TAL) contingency landing sites the night-time crosswind limit is 12 knots.

Headwind not to exceed 25 knots

Tailwind not to exceed 10 knots average, 15 knots peak

Sun angle on final approach not within 10 degrees in azimuth and 0 to 20 degrees in elevation

In addition, a good-sense rule is in effect states: "Even when constraints are not violated, if any other hazardous conditions exist, the launch weather officer will report the threat to the launch director. The launch director may hold at any time based on the instability of the weather."

Source
Kennedy Space Center news release for October 4, 1995.

What Students Will Need to Know
NASA Space Shuttle Launches

NASA weather instrumentation

Space Shuttle Weather Launch Commit Criteria

Contingency Landing Criteria

End-of-Mission Landing Weather Criteria

Online Weather Resources
Latest KSC Area Weather

Space Science and Engineering Center (SSEC) Realtime Data

Penn State University Weather Pages

Current US Weather

The NOAA Weather Page

WebWeather