The prediction will be based on your local area, because the weather station itself computes this from the readings it takes. Is it an indoor station? If it is, it can only go on atmospheric pressure and whether it's going up or down, in which case it's as reliable as an old-fashioned barometer.
If it has outdoor sensors for temperature and humidity, it can use those readings too, and therefore becomes a bit more reliable.
It really depends on what it can do and how much you paid. Indoor stations costing less than fifty quid are really novelty items, but the barometer will be quite accurate and will give you a reasonable guess at the forecast.
Outdoor stations sold by the likes of Maplin for £40 to £100 are a lot of fun and reasonably reliable. The cheapest semi-professional set-up is something like the Davis Vantage Vue for about £500, and a Met Office standard weather station with instruments and screen costs from about £1000 upwards.