I have been to DLR when it is 100 degrees out and it was hot. But that is not typical! Mid-summer temperatures are in the low to mid-80's on average (see
www.wrcc.dri.edu/cgi-bin/cliMAIN.pl?ca0192 - Period of Record: 8/1/1989 to 12/31/2005).
I just do not get all the people talking about how hot it is at DLR. Yes, sometimes. During a heat wave. But usually it is very pleasant in summer, and a bit warm mid-day - and NOTHING like Florida. We did WDW last June and it was 90+ degrees and humid most days.
And then the summer evenings are fabulous! We do shorts and tee-shirts until midnight - never even bring a sweater. The evenings up until midnight might dip into the high 60's but for the most part are in the 70's.
IMO the summer weather at DLR is not
hot. It is fabulous. If you take hotel breaks mid-day as widely recommended then even the moderately warm temperatures mid-day will not affect you, and you will be fresh and rested each evening.
Almost no rain. Almost no humidity. Temperatures in the mid-to-low 80's and sometimes 90's in the day and 70's in the evening. Nearby walking distance hotels where you can swim and nap. Folks, if you will complain about this, you'll complain about anything. The weather is great in the summer at DLR.