A couple weeks ago I posted my favorite summer textiles, but here are some leather options if that's what you need this summer. All of these have perforation or breathability of some kind to get you through the heat. Of course, remember to always wear your favorite full sleeve hot weather baselayers with any of these recommendations!
Keep in mind that even perforated leather won't save you if it's 90-100 degrees, especially with humidity. These are probably more useful to those of you on the west, or southwest where summers are a bit more bearable. Or for mild temperatures, between 70-80 degrees. The summer leather jacket that I wear is also listed below, with a link to the review so you can see how well she did in 90-100 degree dry California heat.
I know there aren't very many options for us when it comes to leather, especially perforated/ventilated ones. Hopefully one of these will work well for you.
Laguna Evo Perforated
$499.95 MSRP, 4 colors, Euro sizes 40-54 (~US2 - 16)
First up, the white jacket above by Dainese. Don't worry, it's also available in black. Aside from all the lovely perforation you can see on the chest and the back of the jacket. The entire surface isn't perforated, but key panels on the chest will provide airflow. Fitment wise, it's your classic hourglass, with a length below the waist. The bust isn't that generous, so if you have a larger than average bust size for your height/weight, then you may want another one the options below. I would still wear a Euro 42 (US 4), but the chest space is definitely a bit snug for me, it doesn't fit anything like the now discontinued Cage.
GP Plus R
$399.95 MSRP, 2 colors, Euro sizes 38-50 (~US 0 - 12)
The GP Plus R also has a typical hourglass fit, but starts down at a full size smaller than the Laguna Evo. I like how this one fits, not too slim, not too broad. If you have a fairly proportionate body type, then this should fit well. The length is nice, also sits right above the hip. I'd say it has a more generous bust fitment. If I needed another leather jacket, this would be one of my top choices. There is no removable liner with this one.
$499.95 MSRP, 2 colors, Sizes Euro 34-46 (US 2-14)
The Galactic is my favorite and current summer leather jacket. Ventilated with a removeable waterproof liner. Read my full review here.
$499.99 MSRP, 2 colors, Sizes Euro 34-46 (US 4-16)
The Ignition is a relaxed, touring / sport touring fit with a more generous and curvy fit. Read my full review here.
$449.99 MSRP, 3 colors, Sizes Euro 34-44
The Xena is the sportiest option for those of you looking for a full race cut leather jacket. This one has a smaller than average fit, I usually wear a 36 in Rev'it and I needed a 38 for this one to accommodate my bust (37").