Lightsoft Weather Center (LWC) is the BMW of Weather Station Software. After finding Davis Instrument's WeatherLink for Mac utterly unsatisfactory, I investigated all the Mac Weather Station software offerings about a year ago. Even then, LWC was head and shoulders over its competition. Version-2 incorporates a complete redesign of the architecture to vastly improve performance and reliability. It also has some "gotta-have" enhancements that leaves even its PC competition in its wake.
Even the development version of LWC-2 was stable for weeks at a time and was very forgiving of Weather Station connectivity issues I was having for a while. LWC has very robust and reliable Internet upload capabilities. It not only does the "required" upload to Weather Underground and CWOP, but it provides you with detailed information about how the processes are going. There is even a supplied AppleScript that will provide Growl announcements should your Internet services have a problem.
Where LWC really shines over the competition is in its graphing capabilities. You can create very complex graphs using multiple sources of weather data. These can be used for something as complex as graphing parameters related to the onset of precipitation or as basic as when to open and close your windows by comparing indoor and outdoor temperature. Folks who have custom weather websites can display these custom graphs on their website to provide unique information to their website viewers that simply isn't possible using other software.
LWC is built for Mac only using Apple's Cocoa development environment. So it has no baggage for Windows portability and no legacy code that reduces efficiency. It also takes advantage OS-X capability of multi-threaded applications. That means LWC will really scream on the fastest Macs with multiple cores and/or processors, and because of OS-X's superior resource management, it won't hog older machines unnecessarily. LWC runs fine on older Mac so that you to "recycle" an old Mac as a dedicated Weather Station manager. However, it also is a "good citizen" with other Macintosh applications. So you can run LWC on your Mac workstation and have it seamlessly take care of your Weather Station even if you run CPU hogs like graphics applications. That way you can keep an eye on the weather no matter how you use your computer for on a daily basis.
LWC has been a commercial product for several years and an enthusiastic community of loyal users has sprung up around it. If you have a question about LWC or weather matters in general, someone on the LWC forum is bound to have at least a helpful pointer to get you unstuck. That's really, really important since weather stations are complex and cantankerous beasts and technical support is hard to find and rarely all that helpful. The LWC forum is by itself a reason to use LWC, but its very existence is testimony to how good LWC really is. Like the Mac itself, it takes an outstanding product to make people passionate about it. LWC is truly such a product. If you have Mac, don't settle for anything less!