Have we seen the best of Summer already?
At Leeming in North Yorkshire, mean maximum temperatures for June came in at 19.9C, almost 2C higher than the June average. That makes it the warmest June since 2006. Sunshine was well above average, but with rainfall only just below the average coming in at 48.2 mm (Average 54.5mm).
Across the UK it has been the driest first 6 months of any year since 1953.
And according to preliminary CET (Central England Temperatures) figures, it has also been the warmest June since 2006.
Looking back through the climate records, one thing stands out. Long periods of dry weather in Spring and early summer often means the rest of summer is much more unsettled. There are exceptions to this rule, like in 2003 and 1976 to name but two, but the odds are stacked against a continuation of dry and warm weather through the rest of summer.
And there is a reason for this.
The Jet stream, a ribbon of strong winds in the upper atmosphere, controls our weather and is responsible for Atlantic depressions and areas of high pressure, leading to wet and dry weather respectively.
The Rocky Mountains in North America act as a barrier to the jet stream, and as air blows across the mountain range, a series of waves are produced downstream.
When the jet stream is at its strongest, the waves pushing eastwards from this mountain range are flat. This is what we call a 'mobile westerly' with weather systems bringing rain, followed by a couple of days fine weather, and then another weather system, and so on. Typical British weather in fact.
But when the Jet stream is at its weakest, the waves are shorter, causing a series of much more pronounced peaks and troughs in a much more 'meridional' or north-south pattern.
In this situation, a ridge of high pressure can get stuck over the UK, leading to persistent dry weather, which is what we have had for the last few months. Conversely when a trough becomes established we can have weeks of wet weather.
Interestingly, the wavelength of these peaks and troughs in our atmosphere tends to get shorter as we head into summer. So if a ridge (dry weather) has dominated our weather in spring and early summer, it is likely to move westwards into mid-Atlantic, leaving the UK under trough (unsettled) conditions. And as we head through early July it is common for this weather pattern to remain for the rest of July and August.
Currently the pattern is certainly shifting, as the upper trough starts to position itself across the UK in the next few days, with weather systems bringing rain in from the west in a more typical mobile-westerly set up.
It's for this reason that the weather is expected to be much more unsettled during the first half of July. Only time will tell if this change will last for the rest of summer.
Hello, I’m Paul Hudson, weather presenter and climate correspondent for Ö÷²¥´óÐã Look North in Yorkshire and Lincolnshire. I've been interested in the weather and climate for as long as I can remember, and worked as a forecaster with the Met Office for more than ten years locally and at the international unit before joining the Ö÷²¥´óÐã in October 2007. Here I divide my time between forecasting and reporting on stories about climate change and its implications for people's everyday lives.
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