I hate the heat, and have sworn off of summer visits. My last January trip saw nights in the 20's which I loved, but might not have appreciated if I was visiting Florida to get away from winter. I was still driving around with my top down!
The last time I went in September it was still really, really uncomfortably hot ...
Completely agree!
I agree. Given the choice between a late January and late September WDW visit, I'd pick late September. Crowds are similar, weather is very different. Fundementally, it comes down to a choice between visiting the parks in a jacket or in shorts. I'd rather visit in shorts.
Given that choice, I'd take January by a mile!
For me, January vs September means visiting in shorts and being comfortable (January), or visiting in shorts and feeling like I'm suffocating in the relentless heat and stifflingly sticky, muggy humidity and at risk of collapsing from heat stroke (September).
The average WDW high in January is 71 degrees which is only 6 degrees hotter than my ideal "neutral" temperature of a comfortably cavelike 65. The average overnight low is 47, and it is usually in the 50's or low 60's at night when the parks close, which is VERY comfortable for me and not cold enough for me to feel the need for long pants and/or a sweater or jacket.
September, on the other hand, has a relentlessly uncomfortable (for me) average high of 90, which is almost as bad as the June/July/August average highs of 91/92/92. I can take a nice shower, walk outside, and immediately feel like I've just stepped into a stupid bloody unbearable sauna and need another one.
And the average overnight low of 72 in September offers little relief, as it is usually hotter, more humid, and muggier than this when the parks close. (more like upper 70's/low-mid 80's at night in the parks). What I am craving for instead is 65 (or lower!) to match the home AC settings I am used to and acclimatized to.
I have wintered in Florida for the past 7 seasons, and have rarely if ever experienced weather I would classify as uncomfortably cold; just pleasantly cool. I've certainly encountered more days that were too hot for my liking even in winter than too cold. In fact, I don't ever recall being "too cold" in a WDW winter. If it gets into the mid 40's or lower, I just wear long pants and a sweater, and I'm comfy (except when I enter a building that has the infernal heater blasting, and then I wish I was in shorts and a t-shirt!)
Based on my taste, I'd be miserable in September. I've lived in the south my whole life, and have never gotten used to the excessive heat and stiffling, overwhelming humidity. Different strokes for different folks, etc.
Another nice thing about January is it's the dry season at WDW and there is only 2.91 average inches of rain. And the rain you do get is much less likely to be thunderstorms due to the cooler temps. September has 5.09 average inches, which is not as bad as the ridiculous amount of rain and thunderstorms in June/July/August, but the rain in Sept is still more likely to be accompanied by lightning than in January.
WDW temp and rain averages:
http://www.weather.com/weather/wxclimatology/monthly/graph/USFL0615
My ideal time to start a WDW trip is a few days after Christmas. This allows me to spend Christmas at home with family and friends before heading to WDW in time to see all the Christmas decorations and entertainment before they go away.
PS. I've noticed a lot of southern meteorologists refer to weather in the 50's as "cold" instead of the more appropriate "cool", but blistering hot weather in the upper 80's and 90's as "warm" instead of the more appropriate "HOT". Never could figure that one out!
