Only one forecaster currently believes festival is likely to be dominated by sun – others expect wettish weekend

Pack your wellies if you're off to Somerset at the end of the month, because Glastonbury is probably going to be a little muddy. With two weeks to go before the festival begins, meteorologists are predicting a mixture of sun, cloud and rain.

So far, Glastonbury 2013 doesn't look like it's going to be a sunfest, à la 2010, or a watery nightmare like 2011. Instead, scientists' satellites and simulations suggest the weekend's 137,000 visitors pack both sunscreen and umbrellas.

First the good news: Accuweather's long-range Glastonbury forecast is full of blazing sun. It is predicting highs of around 24C from Wednesday 26 June, with only very occasional showers until Sunday afternoon, when it is predicting thunderstorms.

Unfortunately, Accuweather is the outlier. Although Weather Outlook also foresees a sunny Thursday and Friday, its forecast predicts heavy rain on Wednesday, setting the stage for a mucky weekend. Festiweather thinks it will rain on Thursday, too. Both of these are closer to the prediction by Jackone, a climatology nerd at Netweather, who files a detailed weekly analysis of the latest meteorological data.

"Not the best of news," he wrote in his latest update. "Hints of an unsettled period of weather in the runup to the festival … I think a mixed festival is the most likely." Based on fancy CFS models, using Met Office numbers, Jackone expects a "wettish" buildup to Glastonbury, followed by "wet/damp" and a gradual "drying up".

If Worthy Farm does get a little sodden, at least the sun might have had a chance to shine by the time the Rolling Stones take the Pyramid stage on Saturday night. "I don't want to play Glastonbury … in the pouring rain," Mick Jagger complained to BBC News this spring. He recalled watching the Who's rain-soaked performance from 2011: "They said it's really fun, but it didn't look fun to me … I was on the phone saying, 'It's awful'."