Having just returned on February 21st maybe I can help.
On February 13th WDW changes from value season to peak season. Which means the resort prices double. So it's important to check in by the 12th if you want to save money. Disney starts to get busy this time of year. Sometimes the attendence can double. The 3rd week of February is Presidents Week, in Mass this is winter school vacation week. A lot of the states on the east coast and some of the mid-west states have this week off. Lots of people are trying to escape winter, so with the kids on vacation from school this is a perfect time. The dates do vary from year to year, usually it the second week that the season rate changes.
With this being peak season, the airlines also up the rates. Flights can sometimes double in price.
As to the weather it can be iffy, usually weather is starting to improve by this time, but you never know. We hit perfect weather during our trip. Cool in the evenings 60's, warm during the days 70's and low 80's. My Grandchildren swam everyday. Pools are heated.
