I noticed a few posts lately on WXSIM, and thought I'd pop in!
Also, after a summer of work on it, I've released Version 10.0, a major upgrade. (There's a $30 upgrade fee for this one - the first upgrade fee after more than 50 free ones in the last several years - otherwise no price change). See www.wxsim.com
if you'd like a look.
Also, I've noticed several questions, about whether it works in various places, whether you can try it out for free, etc. and thought I'd give some quick answers:
First, it's really not comparable to anything else. I haven't seen any software that attempted to do the same thing. It's an interactive local weather model for your home computer, which I can customize for your own location. It's definitely a forecasting tool, with temperature and humidity being its strongest points, but it's also very educational and interesting to run in an experimental or hypothetical mode. Many of its other outputs, like cloud changes and precipitation, are largely based on external data you feed it, from big models like GFS, NAM, and NGM (the first two are only in the U.S., but GFS, fortunately covers the entire earth and the data is freely available on the internet).
The program can look "busy" or complex when you first see it, as it has a huge number of features. There's plenty to learn. While it's not for everybody, I urge you not to be "scared off" by the apparent complexity, though, as it's very user friendly (well, considering what it does, anyway) and retains the core simple options that it had before the days of the internet (I've been working on it since 1982!). It just has a lot more options now!
Basically, the program works anywhere on earth. I went to great pains to test in in a wide variety of climates, locations, and elevations. I've customized it in both the Northern and Southern Hemisphere's, deserts, islands, and even mountain locations, with good success. Some places are harder than others, of course!
The software itself is totally free, with no time limits. The registration fee (about $75) covers something really unique: several (sometimes over a dozen) hours of my time, and correspondence directly with you, to customize numerous parameters (stored in a special data file) specifically for your location. In many cases, I analyze your own home weather station data (definitely including Weather Display!) to make it as specific to your location as possible. You can run the program otherwise, but it will be much less accurate and certain features naturally won't be available, because they make no sense without customization. The downloadable package includes sample customized sites so you can see what that means.
It doesn't run on its own, but does require a fair amount of user input and interaction. I (and quite a few users) regard that as a good thing. It's enjoyable, educational, and valuable if you want to be involved in the forecast process, and really understand what's going on, and the factors involved. It's not the kind of thing that provides an easy automated forecast, and if it were, it certainly wouldn't be nearly as accurate.
Accuracy depends heavily on user input. That said, once you learn to use it, the results are pretty consistent in most situations. You'd get very nearly the same forecast I would. Actually, as you learn more about what factors really matter in your local climate, you should get better and better. In many cases (admittedly not all), its accuracy (once you understand how to use it) can exceed (usually by just a little) that of local official forecasts, mainly in the short term. I've studied this considerably, recording hundreds of forecasts, and you can see the results at www.wxsim.com
By the way, I'm not a company. I don't have any employees. I'm a 45 year old high school physics, astronomy, and meteorology teacher (and weather and astronomy nut!) near Atlanta, Georgia. I love my teaching job (and wife and two kids!) and do this on the side. It's somewhere between a second job and a hobby. I enjoy meeting people all over the world, corresponding with them, and learning a great deal about their climate! Kind of a virtual travel experience! The program is a 20+ year "labor of love" that I undertook just for the challenge and joy of seeing if I could do it! I average about four or so orders a month (it varies), so if you order, there's about a 50-50 chance I'll still be working on the one before yours. In any case, I almost always deliver the files within a week.
Thanks (to Stuart, Brian, and whoever else) for the privilege of having a forum here for this software!