Thursday 28th May
Wednesday was another day when the temperature reached a peak that surpassed the heatwave threshold, with a high of 30.9C at 17.07, down 2C on the high of Tuesday. The cooler easterly air stream was the reason the high was below the peak of Tuesday. The Met Office uses a temperature of 30C to describe the day as ‘Hot’ and we have now had four consecutive days that reached or exceeded that particular threshold. The heat was slow to dissipate overnight that once again was very warm with a minimum 14.9C at 04.12 early Thursday. The maximum was 13.6C above my long-term average and the minimum 7.9C above average.
Thursday arrived with sunshine after sunrise in Marlborough at exactly 05.00, but a little more muted than recently, thanks to thin high cloud, which is likely to build after midday and thicken during the afternoon, ahead of a cold front arriving from the west. The recent, dominant anticyclone is slowly edging away to the east and as it does so the wind direction will slowly veer from an easterly quadrant earlier today, to south and then later this afternoon, to have a more westerly component. This will indicate the signifiant change in our weather after the recent heatwave, which will result in temperatures slowly returning to nearer the average for late May. The barometric pressure has dropped another 4mb with a reading of 1021.5mb today at 08.00, down 10mb since its peak on Sunday.
The soil tempetrature at a depth of 5mm read 23.1C at 08.00, a fraction down on its peak of 24.0C on Tuesday morning.
I attach part two of the recent Met Office publication on collecting weather data
Weather stations
At the core of the UK land surface observation network are weather stations. These stations are primarily tasked with collecting information about the present state of the atmosphere, which is essential for producing accurate weather forecasts. These observations provide comprehensive and frequent measurements across a wide range of meteorological variables such as temperature, precipitation and wind.
Stations meet varying needs across the UK, such as long-term climate monitoring, site-specific temperature and wind measurements for customers, and a dense rainfall network – which includes data from third-party sources – critical for water management and flood forecasting. Together, these stations ensure the UK observation network meets both operational and scientific demands across sectors.
Comprehensive UK coverage
Weather stations are strategically distributed across the UK, aiming to provide near-uniform coverage where possible. The network is designed to capture key features, such as the weather associated with typical low-pressure systems and frontal activity that frequently influence the UK.Choosing where sites are located
Station locations follow strict criteria to ensure data is as consistent and reliable as possible.
The ideal location is level ground, free from nearby trees, buildings, or steep terrain that could influence measurements.
Steps are taken to balance the need for observations from a wide variety of locations – such as in cities – with the need for observations that can be as representative as possible of a wider area. For example, frost hollows could result in low overnight readings while windspeeds from on top of hills may not reflect wider conditions.
The Met Office takes steps to avoid these influences on the land observation network to ensure the data is suitable for operational weather forecasting as well as long-term climate monitoring.