We've still got some warm weather ahead of us, hence Candice's tip:
On warm days, I'm worried about accidentally locking my baby in the car after I buckle him in. To make sure that never happens, I usually crank up the car and get the a/c going to cool the back seat instead of waiting until I get him buckled, things loaded, etc. However, once cranked, I immediately roll down the window *just* to be sure that I won't lock myself out of the vehicle.
Smart, especially if your car doesn't have keyless entry.
We've talked about this topic before — it's such a basic parental fear. I think most of us feel it!
Related: Avoid locking your keys in the car