I didn't read through the whole thread, and I'm not one to suggest any type of jackets or anything for hot weather because I usually don't wear a jacket once it gets past 70* here in NY, and I regularly wear a highly ventilated half, 3/4 or modular helmet....
Side note: I'm thinking about getting a mesh jacket
with a liner for the sunny days like today that are low 50s to mid 60s, and MAYBE for hot days without the liner... but I'm still not 100% sold on it yet. I'm mostly thinking about my tattoos and how I don't want them to fade to crap really quickly from me getting super tan from not wearing a jacket in the summer and staying as cool as I would be if I were NOT wearing a jacket at the same time.
....
BUT, I am all about hydration. I have had problems fainting on super hot days, vacations to Florida, and even on a boat for the Red Bull Air Race in NYC two years ago, due to heat exhaustion/dehydration and not "feeling thirsty" or having water (or anything else) available.
So I have this to offer, because you're a lady, and I'm assuming you carry a purse of some sort... or find it necessary to carry
something, anything, that you might need for wherever you're going.
It's a small MESH hydration
backpack.
This one, to be exact.
I don't have that particular color, but I do have
this one. It's small enough to fit only the things from my purse that I need, my e-reader/tablet (for when I'm at work), an extra 32oz bottle of water and some snacks. But it also has a mostly thermally-protected special pocket and attachment points for a 3 liter hydration bag and hose.(Whether it be camelbak, EMS, or what have you.)
After a trip last year that did not bring us past a gas station or any kind of rest area that could provide at the very least, water, for almost 2 hours, I will not leave on a trip without it (or my other non-mesh one). For me it means backpack tan, but I'm okay with that.
For the cooler months and trips at night I have another similar pack. It's not mesh but has A LOT of reflective stuff on all sides, it also has the special pocket and hooks for a hydration bag, but I haven't used a hydration-jobbie in it yet... It's an Osprey "Daylite" and it's a couple years old, I don't know what the new ones look like, or if they changed the name of the pack recently though, but I'm sure you can Google it. It doesn't quite have all of the features of the brand-spankin-new Jansport, but it's good enough for short trips, and travel to work and home. I have found that it's very warm on hot, sunny, humid days while hiking though, which is why I bought the new mesh pack.
I bought both from Zappos.com because all of the local hiking/outdoor sports shops around here only had giant trekking packs, and tiny camelbaks only meant to hold water. Regular backpacks didn't work either because I wanted a chest strap, or even a chest strap and a "lap" strap.
(The nice thing about the Jansport is that the lap strap has zipper pockets, in which I usually keep chapstick, my license and a debit/credit card for easy access.)
Side note #2: My pet carrier is full from the manual (and NY paperwork), 8ft cable and u-lock, disc lock, extra gloves, scarf, scooter cover, rain jacket, sometimes a change of clothes or shoes, and, of course, an emergency bottle of water, which does not leave me room to shove my purse in there without the possiblity of squishing my cell phone to oblivion... so I ALWAYS have some kind of pack instead.