The go-to advice in this city is always "to layer," which isn't all that helpful when it's 75 degrees and sunny in the Mission and a chilly fog pit in Cole Valley. A new android app tackles these tricky microclimates, telling you exactly how hot/cold/foggy/sunny it is across this 7 mile by 7 mile city of ours (yes, that's where 7x7's name comes from). Powered by Weather Underground and created by R/GA San Francisco, SF Weather provides real-time and next day conditions and forecasts in 18 different neighborhoods. They're only on Android for now, so Android users (sadly, 7x7 HQ is without one), tell us what you think (it's free). They could be rolling it out to iPhones (with a real-time fog overlay feature) soon if there's enough interest. Download it here.