Glastonbury 2014 weather: don’t forget your wellies!

So far, June has generally graced our shores with high pressure, giving many of us warmth and sunshine for the first summer month.

However, with Wimbledon underway and Glastonbury taking place in a few days, the British weather wouldn’t live up to its reputation if rain wasn’t on the horizon.

In the Channel 4 News newsroom, I’ve already had a few dedicated Glastonbury festival goers perched on the end of the weather desk, hoping that their trip won’t turn into a muddy hell.

Whilst I love to be the bearer of good weather news, Glastonbury has some rain heading its way later this week. 

Goodbye high pressure, hello low pressure

Up to now, June has been dominated by a blocking high pressure in the atmosphere, with the jet stream generally nowhere near the UK.

This blocking high pressure has acted as a defender of rain-bearing weather systems, so aside from a few showers or cloudier skies, most of this month has been fine and warm.

However, in the coming days, the jet stream is going pick up speed and move close enough to spawn an area of low pressure that will slowly drift across the UK from late Wednesday onwards.

Whilst confidence in low pressure affecting us later this week is increasing, there is still a lot of uncertainty about its position and orientation, which will influence the intensity and longevity of any rain or showers.

My current feeling is that low pressure will form over Ireland on Wednesday, before slowly pivoting and drifting across Wales and the southern half of England during Thursday, Friday and Saturday – giving showers or even a longer spell of rain in the process.

What does this mean for Glastonbury?

At the moment, it looks like Wednesday and much of Thursday will be fine and dry, with spells of sunshine and temperatures reaching around 21C.

However, as low pressure drifts in later on Thursday, heavy showers are likely during Thursday night and through Friday, with an outside chance of a rumble of thunder.

As for the weekend, Saturday looks like there’ll be some showers too, but they’ll probably be lighter and more infrequent than on Friday. For now, Sunday looks dry with sunny spells.

How muddy will it be?

The key point to remember is that we’ve just had the wettest winter on record, with Somerset bearing the brunt of the rain and flooding. As a result, something called the soil moisture deficit is still abnormally low.

Soil moisture deficit is measure of the amount of moisture in the soils. The lower the deficit, the more water present and vice versa.

The Environment Agency’s monthly water situation report for south west England shows that the soil moisture deficit for Devon and Cornwall at the end of May was just 6mm, compared to the average of around 30mm.

This simply means that the soil has a lot more water in it that would be normally be expected at this time of year.

With the soil wetter than normal, the ground is more sensitive to any downpours than would normally be the case. Therefore, a relatively moderate burst of rain could translate to more mud than you might normally expect to see – especially when thousands of people are constantly walking on the ground.

So, wellies at the ready and follow me on Twitter to get the Glastonbury weather updates as the week progresses – @liamdutton