BBC monthly outlook
Often unsettled but turning drier
Saturday 28 September – Sunday 6 October
Mostly unsettled with a dry, cold spell midweek.
Much of England and Wales are in for a wet and windy weekend as a frontal system sweeps across from the west on Saturday evening into Sunday. Widespread heavy rain bands and perhaps a few rumbles of thunder are likely, first in Wales and Southwest England, and then spreading across into the Southeast on Saturday night. Strong wind gusts are expected across the South, especially on the Channel coast and later in coastal East Anglia. Meanwhile, Scotland and Northern Ireland will likely escape much of the heavy rain, with the majority of precipitation staying south of the central belt.
Another frontal system is expected by Monday afternoon and into Tuesday, following much the same path as the fronts from the weekend, keeping Wales and most of England wet and breezy. However, this system is not expected to be as potent, so overall there will be less rain and winds. Again, the northern half of the country will escape the heaviest rain and winds will be light, but shift to northerly on Tuesday. These northerly winds will then spread southwards Tuesday evening, bringing a blast of colder air from the north.
A cold start for most Wednesday with temperatures in the low single figures. High pressure will bring a brief, but chilly, respite to the recent heavy rain for a few days midweek, but frontal systems are expected to return heading into next weekend as the remnants of Hurricane Lorenzo move near Iceland and weaken the high pressure ridge over the UK. Friday through Sunday is likely to be milder with some south-westerly winds bringing in more tropical air. Things will also turn wetter with active fronts pushing in from the west.
Monday 7 October – Sunday 13 October
Staying wet and windy for most places. Milder.
Heading into the first full week of October, the weather pattern is expected to keep things unsettled across the UK with low pressure tracks moving overhead or just to the north. The jet stream, a ribbon of fast moving air in the upper atmosphere that drives weather systems, is expected to strengthen over the North Atlantic, bringing fast-moving frontal systems into the UK from the west and southwest. These will keep things wet and windy for most of the country, although with high pressure just to the southwest, a few dry and calm interludes are likely.
The temperatures will tend to be near or just a bit above average overall, with frontal systems dragging milder tropical air up from the southwest. This will most often impact the southern half of the country, but this milder air will reach Scotland at times too. However, Scotland will most likely be on the cooler side of average temperatures, as these warm pulses will be short-lived.
Confidence is a bit lower than normal for this range, as there is still a lot of uncertainty on how the atmosphere will react to the remnants of Hurricane Lorenzo in the previous week. There is a 30% risk that the jet stream may not strengthen much as Lorenzo weakens, which will keep high pressure ridging stronger into Northwest Europe and the UK. This will push active frontal systems off to the north and low pressure into Scandinavia, leading to an overall drier but colder picture.
Monday 14 October – Sunday 27 October
Gradual shift into a more settled, warmer pattern.
Unfortunately, due to Atlantic hurricanes and a few other tropical weather patterns, forecast confidence for mid-to-late October is rather low at the moment. We currently expect that the more active low pressure tracks across the UK from earlier in the month will gradually get pushed out of the area by encroaching high pressure as we head into the second half of the month. This is likely to be a gradual shift that takes place over several days as opposed to a more abrupt change.
As Atlantic hurricane season winds down as we go deeper into autumn, this should allow a stronger ridge of high pressure to develop in the Atlantic. This will bring a reduction in the number of weather systems that bring wind and rain to reach the UK. This should also bring in some milder air, especially into the South, but this is highly dependent on the exact location of the high pressure. If it tends to linger further out to sea in the west, then chilly northerly winds will prevail (although the Southwest will likely stay relatively mild).
However, this comes with a rather large caveat that Atlantic hurricane season may not wind down. The typical Atlantic hurricane season lasts until November 1st, so we may well see further strong hurricanes develop. These storms can strongly influence the weather patterns even thousands of miles away over Europe. There is currently quite a high risk (40%) that low pressure tracks will remain over the UK and things will stay more unsettled for the rest of the month.
We will look deeper into the second half of October and continue to monitor Atlantic hurricanes activity.