I have an April baby and a September baby so I have experience with both ends of the spectrum. The seasons of both final trimesters were as polar opposite as you can get.
I for one am a bit of a weirdo and loved being pregnant in the summer. I think growing up in Sydney Australia conditioned me to love the heat; something I lament that I live in Minnesota because of it. You know those days when it is hot and you have to air out your car before getting into it otherwise it is crazy hot? Instead of airing out my car, I jump in, quickly close the door, and relish the heat. I don't get a chance to do that much anymore because I have my kids to think about, but I still do it when I don't have them with me. For me, being pregnant in the summer was great. The only time I really felt overheated was when I exerted myself physically for too long and in the last trimester, I wasn't working out much.
The best part of a summer pregnancy is the clothes. How great it was to be able to throw on a big ol' maternity sundress and flip flops every day! That was my summer uniform and I loved it.
Me at 34 and 38 weeks pregnant with Hailey
Dresses are awesome when pregnant mostly because pants are so annoying. When you're belly is so disproportionately large, it is hard to find pants that stay on well, are comfortable, and look half way decent. Dresses take all that away and just drape over everything so nicely. Like many pregnant women, my feet swelled a little during my pregnancies. This meant that my regular shoes were a little tight. In the winter this was a pain because most of my shoes didn't fit so well. In the summer however, I was able to rock my old flip flops day in and day out without any discomfort.
Both kids were timed well in terms of birth months because both were born during transition months in our state. This meant that as itty bitty newborns, they didn't have to deal with extreme temperatures on either end of the thermometer.
Despite this whole blog post, I know that whenever Mike and I do decide on having a third, we won't be trying for any specific time. Pregnancy is short in the grand scheme of things, even if it doesn't feel that way at the time. Lucky for me, I now have a maternity wardrobe for both cold and warm weather and everything in between. If you are more of a planner than myself, and are wondering when is best, I think it really depends on you and also the area where you live. I may have been happy being pregnant in the summer, but I don't know if I could say the same if the high was regularly over 100 degrees.
Regardless of your timing, try to remember that you won't be pregnant forever. Sounds simple, but that is a difficult concept to imagine when you are newly pregnant and forty weeks sounds so long. It is even harder to imagine when you are in the last few weeks and each day drags on. I may need to come back and read this for a little reminder someday because I am not always the best at taking my own advice.