For me it all depends on what I'm spraying. Heat, humidity, rainfall, irrigation in the lawn.......all of these play a factor. (It's been consistently over 90 here for over 6 weeks now)
I usually stay away from any chemical with a temp restrictions like 2-4-D if it's going to be over 85 at any point during the day. For my area that means we stop using 3 way products and the like around March or early April and don't even look at them again until October.
Every chemical is different, and most of them have always been fine for me regardless of temp as long as the lawn isn't stressed for other reasons like lack of rainfall. You can usually find an alternative chemical for most things.
Most of the newer, synthetic chems like Quicksilver, Dismiss, and Drive are even safer for the lawns, albeit a lot more expensive than the older stuff.
There are so many variables to this stuff. It helps to have a university/extension guy that you really trust to ask questions when needed. I've always had a resource from UGA that offered to take any phone calls we needed. He's the weed specialists for one of the UGA campuses here(and does most of the turfgrass research and contributes to writing our annual guide book) and the guy really knows his stuff. I always call him whenever I'm unsure about something, but that becomes more rare as the years go by.
NC state has a great reputation for their Hort program and you may want to see if they have a yearly publication. In GA we have one called "Turfgrass Recommendations for Professionals." We get a copy every year for being members in the GA Turfgrass Association. It's got all kinds of info on chems for weeds, disease and insects and reactions of different grasses to all of them. We carry them in the trucks for a quick reference guide.
