Whoa, I lived in New Orleans and I can tell you that they will suffer when
the real heat hits.  With the screened in porch, I can offer one solution.
Get some plexiglass and put it on the bottom of the screen so they can't
get to the screen (for 2 girls, 24 " high should be enough to prevent them
from escaping).  then, get a baby pool and fill it with water.  Let them
rum free and then they can play in the water if it gets too hot.  Also, get
some ceramic tile.  Ceramic stays cold (can even put it on an ice bath if
necessary, but don't want it too cold) in shade adn that can provide a
place for them to lie on if it gets too hot.  without these things, when
that august no breeze day hits 95+ temp with 95+ humidity, they may (and I
say may) not make it.
 
A fan wouldn't hurt either, but then I do not know if your babies chew on
cords.
 
Also, try to make sure you get the hard plastic pool, blow up pools they
may chew on.
 
Hope this helps
Paige
[Posted in FML issue 2692]