Thursday 9th July
The sun was relentless on Wednesday as soon as it got out of bed, that it eventually pushed the temperature to a maximum of 32.5C at 18.12. This high was a significant 9.6C above my long-term average making it the hottest day since 26th June. The sunshine was wall to wall that once again resulted in High UV light. Being so close to the centre of the anticyclone meant little movement of air, a maximum movement, couldn’t be called a gust, was just 9mph at 12.50. The heat was slow to dissipate under clear skies, however, a minimum of 12.6C at 05.31, half an hour after sunrise in Marlborough at 05.01, was just 0.6C above the July average. The breeze fell out just before 22.00 and it has been calm all night and also still this morning, both the high and low anemometers are stationary.
The blazing sun once again greeted the start of a new day on Thursday that resulted in a temperature of 23.2C at 08.00, which made it the warmest start to a new day, at that time, since 26th June in that heatwave. Today and tomorrow will bring the peak of the heatwave as the thermometer edges a little higher.
Under the intense heat the ground is still drying out with an equivalent loss of rainfall in excess of 5mm each day. So far this month the total loss due to evaporation from plant life and the ground is currently 43mm set against the 0.2mm that fell on the 1st, from light drizzle. As the heat builds and the ground continues to dry out, the humidity at the start of each new day, logged at 08.00, has reduced significantly. Today the humidity was 67% compared to that of three days ago of 83% and at the start of the month was 90%.
The centre of the high pressure is slowly relocating westwards, then northwards, that by Saturday will see it centred between Scotland and Iceland. This minor change in position will signify a distinct change in our weather, if only minor. The breeze will the have an easterly component, which means it will have traveled over the North Sea and we will see a gradual, if small, decrease in maximum temperatures. However, not to get excited, as the heatwave conditions are likely to persist right through next week and up to the following weekend that will then eventually bring some relief from the excessive heat, but maximum temperatures are still likely to be a little above average.
There is little sign of any useful rain in the forecast for gardeners, one forecast suggest that there might be light rain showers towards the end of next week but that is a long way off for any confidence in the forecast.
The Met Office released this article yesterday.
A marine heatwave could reach “extreme” levels around parts of the UK later this week, according to the Met Office, raising concerns for marine life.
Long periods of sea heat can trigger mass die-offs among some seagrasses, shellfish and other species, as well as encouraging greater numbers of warm-water creatures including octopus.
The heatwave is currently strongest off the coasts of eastern and southern England, and sea temperatures could reach 4-5C above average in places.
The marine heatwave has been fuelled by the “heat domes” that brought record-breaking air temperatures in May and June, on top of long-term ocean warming due to climate change.
Important marine habitats such as seagrasses and kelp forests are suited to cooler waters and can experience high levels of heat stress when temperatures surge.
This can reduce their growth or even lead to mass mortality events, which could have knock-on effects for species that rely on these habitats.
The UK has experienced marine heatwaves – prolonged periods of unusually high sea surface temperatures – before.
But scientists fear this event could be particularly intense and long-lasting, particularly for parts of the English Channel and the southern North Sea.
“We’re starting to see temperatures now that we would expect to see at the height of summer, [at the] end of August,” said Dr Zoe Jacobs of the National Oceanography Centre in Southampton.