Actually I think 24 hours rain forecasts are pretty good now. Make sure you know what the forecast means: "20% chance of rain" usually means there's a 20% chance of rain somewhere in the forecast region. It doesn't mean there's a 20% chance of rain where you are (the NWS forecaster doesn't know where you are!)

There's a good analogy here. Two week rain forecasts are nearly useless at saying if it will rain. But seasonal total rainfall estimates are a lot better, saying that there will be more or less rainfall than "normal" for spring/summer/fall/winter. Farmers use seasonal forecasts as one factor in deciding what to plant etc. The seasonal rainfall forecasts aren't perfect and they don't bet the farm on them, but the forecasts are definitely useful in increasing the odds of a successful farming season.