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The Impact of Weather on Launch Delays at Cape Canaveral and Kennedy Space Center

This is a work in progress, additional data/revisions will be added over time as new information is available.


What is the Difference Between Cape Canaveral And Kennedy Space Center?

Cape Canaveral and Kennedy Space Center (KSC) are two separate but closely related entities in Florida, , that are both associated with .

Source: NASA

Cape Canaveral is a barrier island located on the east coast of Florida, just south of the Kennedy Space Center. It is home to the Cape Canaveral Air Force Station, which is used for and commercial rocket launches, as well as some NASA launches. Cape Canaveral is operated by the United States Air Force, and it is also home to the Eastern Range, which is responsible for tracking and supporting launches from the Cape.

KSC is a NASA spaceport located on Merritt Island, just north of Cape Canaveral. It is where NASA launches its and where the agency's most famous launches, such as the Apollo missions and the program, took place. The KSC is also home to the Vehicle Assembly Building, the Control Center, and other facilities that are essential to launching and supporting space missions.

The primary difference is that Cape Canaveral is a military and commercial launch site that is operated by the United States Air Force, while the KSC is a and commercial launch site that is operated by NASA.

Weather Delays: All Launches

Weather-related launch delays at Cape Canaveral and KSC are a significant consideration for mission planners and launch teams.

Kennedy Space Center

Launch delays at KSC can be caused by a variety of factors, including weather conditions. The specific statistics for launch delays caused by weather at KSC depend on the time period and specific missions being considered. However, here are some general statistics:

According to the National Weather Service, the average number of weather-related launch delays at KSC between 1990 and 2008 was 21 per year.

The most common weather-related cause of launch delays at KSC is thunderstorms, which can produce lightning and high winds that can damage launch infrastructure and pose a risk to spacecraft. Other weather factors that can cause launch delays include tropical storms and hurricanes, high winds, and cloud cover.

Cape Canaveral

Adverse weather conditions are the most common cause of rocket countdown scrubs, according to meteorologist Mark Burger, the launch weather officer with the US Air Force at Cape Canaveral.

“Roughly 16% of every launch attempt we have at Cape Canaveral gets scrubbed due to weather,” said Burger, who has 23 years of forecast experience. “Roughly 23% of all the countdowns have some sort of weather consideration.”

Source: CNN, August 2022

Weather Delays: Human Spaceflight

Project Mercury

Total Number of Weather Related Scrubs and Delays: 7 Scrubs, 2 Delays

4 of 6 (66%) Mission Launches Impacted by Weather. (Note that the counting of weather related scrubs and delays used here is similar to the current accounting in the Space Shuttle program in that delays prior to entering a launch count are not included.)

Freedom 7 MR-3: First US Manned Flight (Shepherd) (1 Scrub)

Delayed at T-15 due to low clouds obscuring the view of the launch area. Visibility improved 20 to 45 minutes later. Scrubbed for 1 day.

Liberty Bell 7 MR-4: Second US Manned Flight (Grissom) (2 Scrubs, 1 Delay)

The launch was originally scheduled for July 18, 1961, but was rescheduled to July 19 due to unfavorable weather conditions. The launch attempt of July 19, 1961 was cancelled at T-10 minutes due to continued unfavorable weather. The launch was then scheduled for July 21, 1961. Preparation proceeded normally through the 12 hour planned hold. Weather evaluation at this time affirmed favorable launch conditions. At T-180 minutes, a planned 1-hour hold was called for another weather evaluation. Other holds occurred due to other problems. At T-15 Minutes, a 41-minute hold was called to await better cloud conditions. The launch count then proceeded normally.

Friendship 7 MA-6: First US Manned Orbital Flight (Glenn) (4 Scrubs)

Of the 33 days on the pad, 7 days of weather delays. Pre-count was completed on 27 Jan 1962, but weather cancelled the launch count at T-13 minutes. Pre-counts were again started on 13, 15, and 16 Feb but were scrubbed due to adverse weather.

Aurora 7 MA-7: Second US Manned Orbital Flight (Carpenter) (1 Delay)

T-11 min 15-minute hold for weather (launch area smoke and ground fog). Hold extended for additional 15 minutes for weather. Hold extended for additional 10 minutes for evaluation of atmospheric-refraction data. Hold extended for additional 5 minutes to complete refracto-meter data evaluation. Although the ground visibility at liftoff was limited to one mile, the estimated camera coverage through 250,000 was predicted to be good at the time of launch.

Sigma 7 MA-8: Third US Manned Orbital Flight (Schirra)

Weather forecasts on the morning of October 2, 1962 indicated that Hurricane Daisy might be in position to cause unfavorable weather in area 3-1. Therefore, recovery ships were relocated approximately 215 miles downrange At launch time, weather conditions were favorable in all planned Atlantic and Pacific recovery locations.

Faith 7 MA-9: Fourth US Manned Orbital Flight (Carpenter)

No significant weather impacts were noted.

Project Gemini

Total Number of Weather Related Scrubs and 21 Delays: 1 Scrub, 0 Delays

1 of 10 Missions impacted by weather (10%)

Launch and Recovery concerns: thunderstorms, winds, sea state

Pre-launch preparations affected by lightning and hurricanes


Weather in Western Pacific Recovery Zones marginal due to Tropical Storms Babe and Carla.


1st launch attempt scrubbed due to computer problem, but a thunderstorm was within 1 to 2 miles of the launch pad. Recommend recovery one orbit early due to weather in recovery zone. 1 launch scrub & recovery moved due to Hurricane Betsy.


Dispersion of Toxics may have been an issue during the launch.


Mission terminated early. The importance of planning forecast emphasized. Some difficulty verifying recovery observation due to emergency recovery. There was a great deal of concern with the wave heights and the crew got seasick while waiting for recovery due to sea state.

Project Apollo

Total Number of Weather Related Scrubs and Delays: 0 Scrubs, 1 Delay

Apollo 7: First Apollo Manned Flight (Schirra/Eisele/Cunningham)

Launch winds close to limit

Apollo 11: First Landing (Armstrong/Aldrin/Collins)

Recovery location moved

Apollo 12: Second Lunar Landing (Conrad/Bean/Gordon)

Launch into precipitation and electrified clouds triggered lightning strike to vehicle. The mission continued to a successful conclusion after quick action on the part of the flight controllers and the crew to recover the spacecraft electrical systems.

Apollo 13: Vehicle Crippled (Lovell/Haise/Swigert)

Apollo 13 recovery location moved due to tropical storm

Apollo 14: Lunar Landing (Shepard/Evans/Roos) (1 Delay)

Apollo 14 launch delayed

Apollo 16: Lunar Landing (Young/Mattingly/Duke)

The Apollo 16 mission was shortened 1 day due to technical issues not related to weather. However, this changed the recovery location which significantly improved the weather conditions in the recovery area.

Skylab 2: (Conrad/Weitz/Kerwin)

Thunderstorms developed during previous afternoon, but then continued into night and morning hours. However, storms remained west of area.

Apollo- Test Project (Stafford/Brand/Slayton)

The Apollo and Soyuz spacecraft were launched on the same day with the Soyuz launching first during daylight hours. This necessitated an afternoon launch at KSC during July. Therefore, there was a great deal of concern regarding the potential for thunderstorm occurrence, the ability to predict thunderstorms 8 – 12 hours in advance, and whether it was reasonable to scrub the Soyuz launch at Baikonur due to a forecasted occurrence of thunderstorms at KSC. Although SMG was proud of its capability to predict thunderstorms at KSC, they recommended not scrubbing a launch due to forecast thunderstorms. The launch rules for AST were modifed from the version used in the Skylab missions. aircraft supported Apollo-Soyuz launch to provide measurements to help avoid any triggered lightning. As it turned out, thunderstorms ended up not being a significant threat on the launch day.

Space Shuttle Program

Shuttle Launch Delays Summary by System
Frequency of scrubs by category


Weather Launch Commit Guidelines

The weather guidelines for NASA's I flight test identify conditions to safely roll out to the pad and launch the agency's and spacecraft.

These guidelines include criteria for various meteorological conditions. Weather teams refer to these criteria while monitoring the elements and implement constraints when conditions could affect rollout or liftoff. The criteria are broadly conservative and developed to avoid possible adverse outcomes.

If other potential weather hazards exist beyond those in the guidelines, the launch weather team will report the hazardous condition to the launch director, who will determine whether launching would expose Artemis I to a weather hazard.

Basic Weather Criteria for Roll to the Pad

Do not roll to launch pad if the lightning forecast is greater than 10% within 20 nautical miles of the launch area during rollout.

Do not roll to launch pad if there is greater than a 5% chance of hail forecast in the launch area during rollout.

Do not roll to launch pad if the peak winds exceed 40 knots in the launch area during rollout.

Do not roll to launch pad if temperature is less than 40 degrees Fahrenheit or exceeds 95 degrees Fahrenheit at the launch area during rollout.

Basic Weather Launch Criteria at the Pad for Liftoff


Do not initiate tanking if the 24-hour average temperature at both 132.5 feet and 257.5 feet is less than 41.4 degrees Fahrenheit.

Do not launch if the temperature at both 132.5 feet and 257.5 feet exceeds 94.5 degrees Fahrenheit for 30 consecutive minutes.

Do not launch if the temperature at both 132.5 feet and 257.5 feet drops below a defined temperature constraint for 30 consecutive minutes. The temperature constraints range from 38 degrees Fahrenheit to 49 degrees Fahrenheit, depending upon the wind and relative humidity. Higher wind and relative humidity result in a colder temperature constraint.

In this view looking up from the flame trench at Launch Pad 39B, NASA's Space Launch System () rocket and Orion spacecraft are photographed atop the mobile launcher at the agency's Kennedy Space Center in Florida on March 18, 2022.
Credits: NASA/Kim Shiflett

Do not launch if the peak liftoff winds exceed a range of 29 knots through 39 knots between 132.5 feet and 457.5 feet, respectively.

Do not launch through upper-level wind conditions that could lead to control problems for the launch vehicle.


Do not launch through precipitation.


Do not initiate tanking of the core stage or interim cryogenic propulsion stage (ICPS) if the lightning forecast is greater than 20% within 5 nautical miles of the launch area during tanking.

Do not launch for 30 minutes after lightning is observed within 10 nautical miles of the flight path, unless specified conditions related to cloud distance and surface electrical fields can be met.

Do not launch if the flight path is within 10 nautical miles of the edge of a thunderstorm that is producing lightning until 30 minutes after the last lightning discharge is observed.

Do not launch if the flight path is within 10 nautical miles of an attached thunderstorm anvil cloud unless temperature, time since last lightning, and distance criteria can be met, and if within 3 nautical miles, maximum reflectivity criteria also are satisfied.

Do not launch if the flight path is within 10 nautical miles of a detached thunderstorm anvil cloud unless temperature, time since lightning and/or detachment, and distance criteria can be met, and if within 3 nautical miles, maximum radar reflectivity criteria also are satisfied.


Do not launch if the flight path is within 3 nautical miles of a thunderstorm debris cloud for 3 hours, unless temperature, surface electric field, and radar reflectivity criteria can be met.

Do not launch if the flight path is within 5 nautical miles of disturbed weather clouds that extend into freezing temperatures and contain moderate or greater precipitation.

Do not launch through a cloud layer that is within 5 nautical miles, greater than 4,500 feet thick, and extends into freezing temperatures, unless specific criteria related to radar reflectivity and cloud altitude can be met.

Do not launch if the flight path is within 10 nautical miles of cumulus clouds with certain distance and height criteria. There are additional caveats that could be met for clouds not reaching 23 degrees Fahrenheit.

Do not launch through cumulus clouds formed as the result of or directly attached to a smoke plume, unless more than 60 minutes passed since detachment from the smoke plume.

Do not launch for 15 minutes if field mill instrument readings within 5 nautical miles of the launch pad equal or exceed +/- 1,500 volts per meter, or +/- 1,000 volts per meter, unless specific caveats related to clouds within 10 nautical miles of the flight path can be met.

Solar Activity

Do not launch during severe or extreme solar activity resulting in increased density of solar energetic particles with the potential to damage electronic circuits and make radio communication with the launch vehicle difficult or impossible.

End of Mission Splashdown Weather Criteria

The end of mission and splashdown weather criteria for NASA's Orion spacecraft are informed by splashdown site weather forecasts prepared by the National Oceanic and Atmospheric Administration National Weather Service Meteorology Group in Houston for the Artemis I mission management team. All criteria refer to observed and forecast weather conditions. The mission management team will convene to determine the primary and alternate landing sites about 72 hours prior to splashdown. Splashdown sites are selected based on predetermined constraints related to winds, waves, thunderstorms, and cloud cover for the safe recovery of Orion and for the teams conducting the operations.

The weather criteria for landing/splashdown are as follows:

  • Wind Speed: Average surface wind speed 20 knots or less (33.8 ft/) and peak surface wind speed 24 knots (40.5 ft/sec) or less
  • Significant Wave Height & Wave Speed: 6 feet or less, referring to the average of the highest one-third of waves that occur in a given period, and average wave speed of 25 knots (42.2 ft/sec) or less
  • Thunderstorms & Lightning: No thunderstorms or lightning within 30 nautical miles and no precipitation greater than .3 inches within 30 nautical miles 
  • Cloud Coverage: Cloud ceilings no less than 500 feet, no less than 1 mile for horizontal visibility and no less than 7 miles for vertical visibility. 


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