When should I postpone an even due to the weather forecast?

Question

I'm having a barbecue Saturday July 5th for my daughter's bday. According to the weather forecast, there is a 40% chance of scattered thunderstorms for that day. So far, it has been raining almost every weekend. Today is Sunday, 6 days away from the barbeque. By when should I postpone the celebration due to the weather forecast? I think the weather forecast for next Saturday should be accurate by Thursday but I'm afraid of postponing the celebration and having no rain on Saturday.

Answer 1

You would be correct in saying that by Thursday it should be fairly accurate.  Don't cancel/ppd the event quite yet.  

If the percentage chance of rain continues to increase from 40% as you get closer to Saturday, then the trend that the weather models are leaning towards is staying true and it's obviously likely to rain.  If it stays near 40% or decreases late in the week, then there has been some change in the weather model predictions. This would benefit your party.

If I knew your region for the BBQ, maybe I could help give you a better forecast?