Whenever you hear someone talking about the weather forecast, they refer to the source of information as "they."
Think about it.
You're in an elevator and someone engages you in small talk.
"Tired of this rain."
"But they said it would clear by tonight."
You never hear anyone say "the national weather service is saying" or "Channel 5's forecast calls for..."
It's always "they."
It's just one of those quirky facts of life.
And they say it's supposed to be sunny and warm today.