Few things at work are worse than sitting at your desk and burning up. I'm very lucky that my office is casual enough for cotton skirts and pretty sandals, but even if yours is not, here are some options I think could get a lot of wear the next several months. I'm also pairing them with Seychelles shoes from endless.com since I saw them on Gilt.com today and love the retro style.
The Limited Sheath Dress
Seychelles Kick Up Your Heels Wedge
This dress is made of stretchy cotton and should be pretty comfortable, as well as polished for meetings. If you aren't comfortable going sleeveless, you could add a short sleeved cardigan.
LOFT Tie Waist Shirtdress
Seychelles Liz Sandal
I think the casual material of this dress lends it to a fun shoe that's still classy enough for an office (mine, anyway). The cut of the dress of universally flattering, but those of us with large chests may want to layer something under it since wrap tops are seldom as modest as they appear in photos.
Lands End Canvas Cotton Lawn Skirt
Banana Republic Elbow Sleeve Stretch Skirt
Seychelles Sofia Wedge
This is a lot of gray, but I think it would work and look very classy for presentations and meetings