Since temperatures have been still in the 80's during the day and humid some yet...those nights when the wind picks up the animals do
Even tonight, temps are cooler and nice breeze blowing, if you clip you would need a blanket...and it isn't cold but your horse will feel it with his coat removed.
Me, I would be doing a medium blanket when the drop is 40-50 degrees with no
breeze blowing and definitely
use a blanket when the temp drop is accompanied by the cool winds.
Off during the day, maybe
a sheet in the morning cool damp air, then removed mid-morning as the sun is still warm and temps go to the 60's and or better....
If the horse is t/o, you could use a lighter blanket if it is a weather-proof one...they restrict a little better the air flow with the moisture barrier.
I agree though you want to clip the underside of the neck, bottom of the belly/barrel like this at least....A Bib Clip
This is a High Trace Clip..
My horses used to get this clip... enough protection from the weather to need a medium blanket but gone were the areas that were the troublesome "sweat" regions...
Here is a link to some of the common clips... http://www.masterclip.co.uk/horse_clipping/horse_clip_types.aspx
There are of course many websites with pictures and what to do when guidelines...
Here is a pretty decent article with reference to the Florida weather...and what is done and why... http://www.horsechannel.com/horse-health/body-clipping-277.aspx
Good Luck, happy clipping and better yet...Enjoy your ride!!