We're not sure why Sun's developer Jakob Henner would opt against releasing his new iOS weather app in the hugely popular App Store, but he certainly deserves credit for choosing a unique approach. Described appropriately as a simple weather app, Sun can be installed on your iPhone, iPod touch, or iPad by visiting Henner's website in mobile Safari. Here you'll be prompted to save the web app on your home screen, a step which is apparently required to get started; we couldn't find any way to use the app without first giving it a slot.
In terms of functionality, Sun isn't going to compare with some of the more advanced weather tools available on Apple's platform, but that's not Henner's intent. Rather, it's meant as a quick reference that by default displays only the current temperature of your chosen city along with a simple icon to indicate whether you'll be seeing rain or clouds in the immediate future. Gesture support lets users pinch out to view an equally minimal four-day forecast. In terms of settings, you'll find preferences for units of measurement along with a few themes that change up the app's appearance. There's really not much else to Sun, but if you're looking for an extremely simple way to check the weather, it could be worth a look.