Ghali - thank you! I will def do the blood test in a few months...I have adjusted my ride to early early in the am as well - appreciate your quick response! Best of luck with your rides.
Ryan - thank you! Much appreciated - showing in this part of the world is great because the season is long buy oy - it's definitely a challenge!
It is difficult for horses at the beginning, you have to take your time, after 5-6 months you have to do a blood test to see if your horse is alright. The most simple is to ride early in the morning, or late in the evening.
I live in the southeastern US- really just avoid riding during the hottest part of the day. It's not so much the humidity that's an issue (though sometimes you feel like you're drowning in it!), but the heat and humidity combined. Stick to morning rides or night rides, before the sun comes up/just after the sunrise, or after it sets. Most horses don't have a hard time adjusting to humid weather :)