For me, it seems like the weather tile in SmartTiles is only occasionally up-to-date.
However, in my case, I have my ‘SmartWeather Station Tile’ (the SmartApp from SmartThings) pointed to get its weather data from my BloomSky (using @slagle 's device/app combo), and that NEVER updates automatically. The only time my BloomSky setup ever updates is when/if I click refresh in the BloomSky SmartApp within SmartTHings mobile app.
Not sure if that’s relevant to anyone else’s setup, but if you have your BloomSky in the mix too, you may want to pick something else as the source of your weather tiles’s weather data and see how that goes.
i.e. when I point mine to some other source (e.g. a motion sensor with temp, etc), it pretty much seems to update at least as often as there is a change in the temp.