If I could find a mesh jacket with armor that was comfortable,I would wear one!
I wear leather when 70 or below and a T shirt and High vis vest when it's hot. Try to stay out of stop and go traffic!

 

I wear my mesh armored jacket in temps above 65F. My leather, even though it's vented in several places, is entirely too warm above 65-70.

edit:

If any of your local metric shops carry Joe Rocket stuff, try on a Phoenix 5.0. Mine is extremely comfortable.

 

I wear my leather until the temp gets above the mid 80's. Then I switch to my Tourmaster mesh jacket. Mesh is the best way to go when the temp gets into the 90's and up.

 

Just wear a vest. Yeah, my arms are ****ed if I go down. I don't think it'll be my arms I'm worrying about.

 

LEATHER ALL THE TIME. DRESS FOR THE SLIDE, NOT THE RIDE.
HAVE YOU HAD YOUR WRECK YET? ONLY ONE ANSWER, YES OR NO!
AS LONG AS WE KEEP MOVING, I AM COMFORTABLE IN HEAT. MY RIDES ARE ISOLATED BACK ROADS SO NO STOP AND GO TRAFFIC. TRY TO GET ON EAST TENNESSEE AND NORTH CAROLINA MOUNTAIN AREA WHEN TRAFFIC IS MINIMAL. WE DON'T DO SHORT RIDES. RIDE SAFE.

 

No jacket, just a T-shirt in the summer. I see far more people riding in shorts and wife beaters than I see wearing leather here in the summer.

 

You wearing leather pants too? Leather gloves? Full face?

 

Schott Perfecto 365, same as since 1964...

 

We did an Arizona trip a few years ago in the middle of July, 90-100 degree temps. I wore my Foxcreek vented leather jacket throughout the trip. Nice air flow and did not sweat while wearing it. I wear it now wherever and at whatever temps there are. Plus i feel a safer wearing it. Wore my 8" Red Wing leather boots too!!

 

In the summer I wear my perforated leather jacket until it's mid 90's and above and then just go with a tee shirt.