This outfit proved to be too warm as is, since by the time I wore it we were well into our Indian Summer mini-heat wave. Thankfully I was able to remove the sweater when it got too warm; I haven't always used such foresight in planning my outfits, and have sometimes been stuck with a top layer I can't remove because of bra straps or see-through bits or some other limitation. Or more often, I wore short sleeves and didn't account for it being colder inside.
After years of living in the Bay Area I've gotten better at this, and now I generally take some time to consider how the outfit looks with the top layer both on and off before I commit to it. I'm sure this is an issue for anyone who works in an office, where the inside temperature can be vastly different from what's going on outside. It's no problem if you've just got a jacket on top that you can remove, but if your layers are belted or if the top layer hides some flaw in the clothing underneath, it's important to consider how comfortable the outfit is going to be for the different environmental conditions your day will expose you to. Why plan an entire outfit for 10 minutes of outdoor heat when the rest of your day will be spent shivering in your air conditioned office?
Just in case I fail to plan appropriately, I keep the following emergency supplies in my office at work: 2 jackets (one black, one off-white), 1 sweater, and one closed-toed pair of shoes (in case I need to go in the lab and I'm wearing sandals or peep toes). And because I can be forgetful I also keep a toothbrush, toothpaste, and deodorant, lest I get to work and sit there fretting that there was something important I forgot to do that morning.