Fluffy umbrellas are probably more useful than long-range weather forecasts!
There isn't a forecaster on earth, amateur or professional, who can forecast beyond about 5 days ahead with consistent reliability.
I have the greatest respect for netweather, but they're taking a punt on current trends using long-term patterns and gut instinct as their guide, and at best they'll be right as often as they're wrong.
In other words, no better than chance. Your guess is as good as theirs.