“Forecasts” sounds like “four casts.” A weather pun was printed in the Daily Mail (London, UK) on September 14, 1999:
 
“Two weathermen each broke an arm and a leg in an accident and called from the hospital about the four casts.”
   
The joke involved one weatherman as posted on the newsgroup alt.humor.puns on September 20, 2000:
 
“Then there was the meteorologist who broke both his arms and legs. He called in from the hospital to tell the four-casts.”
 
     
14 September 1999, Daily Mail (London, UK), “10 of the Best Websites” by Elizabeth Stout, pg. 52:
Weathered jokes: http://www.weatherimages.org/ wxhumor.html ‘Two weathermen each broke an arm and a leg in an accident and called from the hospital about the four casts’ . . . You get the idea.
 
Google Groups: alt.humor.puns
“Puns of the Weak” 9/8/00
Stan Kegel
9/9/00
(...)
Two weathermen each broke an arm and a leg in an accident, and called from the hospital about the four casts.  (Mike Bull) 
   
Google Groups: alt.humor.puns
Weather Puns
.(JavaScript must be enabled to view this email address)
9/20/00
(...)
Then there was the meteorologist who broke both his arms and legs.
He called in from the hospital to tell the four-casts.
 
Google Groups: alt.humor.puns
Puns of the Weak 9/14/01
Stan Kegel
9/15/01
(...)
Two weathermen each broke an arm and a leg in an accident, and called from the hospital about the four casts. (The King of Puns)
 
Google Groups: alt.humor.puns
Puns of the Weak 08/30/02
Stan Kegel
8/31/02
(...)
Two weathermen on assignment at the coast each broke an arm and a leg in an accident. They called their TV station from the hospital about the four casts. (Marsha Coleman)
 
Google Groups: alt.humor.puns
Puns of the Weak 06-14-03
Stan Kegel
6/13/03
(...)
A weatherman broke all his limbs and was in hospital with the four casts. (Mike Bull)
   
Google Books
Charlie Chan Meets Tom Swifty:
No Adverb Could Limit, Modify, or Qualify What Happened Next
By T. A. Corbi
Sherman, CT: E-nuphf Books, LLC
2011      
Pg. 25:
“Man with broken arms and legs like weatherman on TV. Both presenting four casts,” predicted Charlie Chan lamely.
 
Facebook
Dad Jokes
July 4, 2013 · Adelaide, SA, Australia ·
A tv weatherman broke both his arms and legs. He had to call in from hospital to explain about the four casts.
(thanks David)
 
Reddit—Oneliners
After a weathermen was in a horrible accident breaking both arms and legs, he had to call from the hospital about the four casts.
submitted October 21, 2017 by wonliners
 
Reddit—Jokes
A TV weatherman broke both his legs and arms in an accident…
submitted December 8, 2018 by hagolu
...he had to call in from the hospital to explain his four casts.