If you would like free weather reports in Apple’s iCal (which can be synced to your iPhone or iPod Touch), there’s good news: Weather Underground supports the iCal .ics format as a subscription format. (It also offers RSS.) And unlike the shareware application WeatherCal (which provides the same service), it is free.
What this means is that you can subscribe to weather reports for any city, and have the forecast appear within iCal. The 7-day forecast will display as a series of all-day events in the calendar. (All-day events appear as headers at the top of each day.) Weather details older than one day are automatically deleted, which is nice; it doesn’t fill up your calendar.