How critical is the weather for the SpaceX launch?

Nasa and SpaceX were due to send four astronauts to the International Space Station late on Saturday - but then the weather changed their plans.

Crew-1 is currently scheduled to blast off on Sunday but their most recent launch, in May 2020, was delayed several days by bad weather.

With lives at stake in a multi-million pound lift off, just how important is the weather to getting space travel right?