Cool finish to June, variable beginning to July
The weather pattern has begun the transition over to a cooler, more unsettled one that is expected to linger for the end of June into the first half of July. High pressure is expected to focus over the north Atlantic with low pressure overhead or just to the north. Changeable temperatures are anticipated, with the end of June likely to see below normal temperatures. The pattern moving into mid-July will remain changeable, though with increasing chances for a few warm and dry periods to develop to mix in with the intermittent shots of cooler and showery weather.
Wet and cool to end the week
A weak cold front will bring spells of showers to Scotland and Northern Ireland on Tuesday into Wednesday. Wales and England remain dry but cool. A more organised low pressure system will slide through late this week, bringing an increase in rain and winds to the UK. Rain is not expected to be as organised by the weekend, but unsettled conditions will persist. A brief warm up is anticipated on Thursday ahead of the approaching low pressure system with readings climbing slightly above normal. Any warming will be short lived as temperatures look to fall back to near to slightly below normal levels over the weekend.
Changeable temperatures with unsettled conditions
High pressure is expected to build in the North Atlantic while another high will be stationed off to the east in Russia. Between these two highs will be an area of low pressure that is expected to favour northern Europe but will extend towards the UK at times. This will produce a more unsettled pattern for the UK with wetter and periodically windier conditions developing. The highest risk for wet weather is likely early in the week as well as over the weekend with the wettest conditions expected in Scotland and eastern England.
The high in the Atlantic is expected to extend towards the UK during the middle of the week. This will allow for warmer and drier conditions to build in as winds shift from northerly to easterly for a period. This isn't expected to lead to extremely warm conditions, as winds from the south would be required, but temperatures a little above normal are likely during this brief stretch. A return to an unsettled pattern with changeable temperatures is likely by the weekend.
This expected weather pattern is one that has high day-to-day variability that can be difficult to predict more than a week ahead. The confidence on the large-scale weather pattern moving into the final days of June into early July is high. Confidence on the specifics is only medium, particularly with the temperatures. There is a smaller chance that high pressure can build eastward and become centred over Germany. This would produce a period of southwest winds, which would lead to above average temperatures and a wetter pattern. Even if this scenario were to develop, temperatures would be warm but would not be especially hot.
Unsettled pattern remains in place
The large-scale weather pattern looks to remain mostly static for the first half of July, with high pressure remaining stationed off to the west over the Atlantic. The trough of low pressure will largely be just to the north. This will allow for conditions in Scotland to remain more unsettled with wet and cool periods anticipated. These spells of cool, wet weather will extend southward into Ireland and England on a more intermittent basis.
The Atlantic high is expected to send more transient high pressure systems across the British Isles into northern Europe at times. These will largely linger for a few days at a time, and will usher in drier and sunnier conditions to interrupt the unsettled conditions. The potential for warmth will further increase if any of these highs settle over Germany. These factors will add up to a changeable weather pattern to continue into July. The warmer, sunnier days are expected to primarily be brief spells early in July. These may become a bit more persistent by mid-July, particularly across England.
The evolution of high pressure in the North Atlantic and its influence across western and northern Europe is the main driver of uncertainty for the forecast. Computer models are persistent on developing a strong area of high pressure over Scandinavia by mid-July. This would be a very warm pattern overall and lead to a potential for heat waves. However, the computer models have performed rather poorly in recent months with their pressure forecasts, thus causing the chances for developing hot weather to be a bit overinflated. A more realistic scenario with a cooler pattern to be interrupted by warm, dry spells is favoured, as the high pressure remains stationed over the Atlantic and struggles to build into Europe. There is a 30% risk that the high pressure builds strongly into Europe, which would lead to warmer weather along with an elevated risk of heat waves.
We will re-evaluate the middle portions of July to look into the potential for any developing heat waves.