The high altitude belt of air flows over the British Isles with its exact position determining how good – and bad – our summer weather is.
In the summer, it is supposed to sit to the north of the UK. But in recent years – particularly last year – it parked directly across the country pulling in heavy rain, flooding and unseasonably low temperatures. The result was yet another thoroughly miserable summer.
Fast forward to 2013 and the all-controlling jet stream has been behaving itself and is sitting just across the most northerly coast of Scotland.
It is this plum position that we have to thank for our run of beautiful July weather that has seen temperatures soar for over a week.
And the even better news is that the jet stream is to move even further north in coming days meaning the warm and sunny weather isn't under threat from rain clouds for a while yet.
A forecaster from Meteo Group in London said temperatures look set to stay well above average for the next few weeks.
After slightly cooler temperatures yesterday, the thermometer will once again soar to 28 degrees by the end of this week.
"It will be around 22C to 23C at the start of this week which will rise to 28C by Thursday and Friday," he said. "The hottest areas will be in the west of the province while coastal areas will be cooler."
The heatwave has come as a delight to some who have relished in the rays but dread to others who have found it difficult to sleep in the past sweaty few weeks.
Sun worshipper Nicola Hill from south Belfast is looking forward to topping up the tan she has been working diligently on.
"I have been loving this weather. I live right beside a park so I have been taking my two dogs there most days and have enjoyed just soaking up the rays. Who needs to book a holiday when the weather is this great?
"I plan to have lots of barbecues and just make the most of it. If missing a few hours sleep because it's so hot means we actually have a proper summer then bring it on."
However, Anne Sloan said she has not been able to sleep for the past few weeks because of the heat.
She said: "I love barbecues and walks on the beach so it is great during the day but it's another story at night when I am trying to get to sleep. No matter how tired I have been I just can't drop off if I'm too hot. I twist and turn all night. We are just not used to weather like this, bring back the rain and wind I say."
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