I just found that if you tap and icon, it brings up a detailed info windos with a 'settings' tab. If you click settings, another window opens which has 'update' tab, where you can specify how often it should update the weather data. You can have it update every 5 min too!
But i find that the data is incorrect by about 2 degrees. The data on weather dot com is much closer to what it reads on my thermometer.