“It’s so hot, the trees are whistling for dogs” (heat joke)

The extremely hot Texas weather has been the subject of many jokes, such as:
 
. “It’s so hot, the trees are whistling for dogs”
. “It’s so hot there that the trees are running after the dogs.”
. “It’s so dry, the trees are following the dogs around for water.”
. “It’s so dry, the trees are bribing the dogs.”
 
The joke dates back to at least the 1940s and the 1950s.
 
 
Google Books
Yank: the army weekly
1945
Pg. 20:
The boys in the South Pacific report it’s so hot there that the trees are running after the dogs.
 
13 December 1953, Charleston (WV) Daily Mail, “they say about Texas!” by Sid Ross & Karl Kohrs, Parade magazine, pg. 9, col. 1:
Your true Texans is not even ashamed to admitthe negative aspects of Texas—particularly its unusual weather.
 
He will be the first to tell you that many parts of the state are so dry the trees follow the dogs around.
(Taken from the books or newspaper columns of Boyce House—ed.)
     
Google Books
April 1972, The Rotarian, “WOOF! The Pfeido Winners,” pg. 14:
“It’s so dry here in Texas that the trees are chasing me (a dog—ed.) around!” — Shelton E. Breeden, Rotarian, Bay City, Texas
 
Google Books
Handy as Hip Pockets on a Hog:
The colorful language of the American Southwest
By Donald Chain Black
Dallas, TC: Taylor Pub. Co.
1989
Pg. 117:
Supernatural figures run from meteorologic (It’s so dry the trees are following the dogs around for water) and anatomic…
   
Google Books
Tickling Catfish:
A Texan looks at culture from Amarillo to Borneo
By Jerry Craven
College Station, TX: Texas A & M University Press
1996  
Pg. 16:
“It’s so dry out here that the trees are taking to follering the dogs around.”
 
22 June 1996, Marietta (GA) Journal, pg. 6A, col. 5:
QUOTABLE: Sen. John McCain, on the worst drought ever in Arizona: “It’s so dry the trees are chasing the dogs.”
 
Google Books
A Collection of Jokes and Funny Stories from the Internet (not appropriate for children)
Edited by Marvin Lebman
Victoria, BC: Trafford
2004
Pg. 158:
It’s so DRY in Texas, the trees are whistlin’ for the dogs.
 
Google Books
Blue-Eyed Devil
By Lisa Kleypas
New York, NY: St. Martin’s Paperbacks
2009, ©2008
Pg. 189:
During the occasional droughts, Houston got so dry that, as a local joke went, “the trees are bribing the dogs.”