Drought in the United Kingdom

These droughts are usually during the summer, when a blocking high causes hot, dry weather for an extended period.

The south east of the country usually suffers most, as it has the highest population (and therefore demand) and the lowest average precipitation per year, which is even lower in a drought.

In this case there is moisture in the soil, but little is getting to vegetation, either because it is frozen (which can occur in severely cold winters in the United Kingdom) or because of very high temperatures which mean that the rate of evapotranspiration exceeds the rate of uptake of water from the plant (which can be seen in the United Kingdom, on hot days, when plants wilt as their stores of water are depleted).

[6] A hydrological drought can occur after a relatively dry winter, when the soil moisture storage, reservoirs and water table have not risen enough to counteract the warm summer weather.

This is why in dry spells the northwest of the United Kingdom actually often receives above average rainfall, as depressions and associated fronts are pushed towards the north.

[4] A severe drought in the United Kingdom needs to have the high pressure in charge of the weather for an extended period, commonly for weeks or even months at a time.

Most often sea surface temperature anomalies in the Atlantic and intensification of the mid latitude westerlies in the Pacific can bring a stable anticyclone, meaning that the pressure can remain above average for weeks, or even months at a time, allowing the heat to build and dry weather to continue during the anticyclonic system.

As of March 2019[update], according to the Environment Agency, due to the impact of climate change, England's anticipated demand for water will exceed its supply around the year 2045.

Martin Baxter of the Institute of Environmental Management and Assessment said, "What we are seeing now is that climate impacts in terms of more extreme weather events are happening more frequently and at a greater magnitude than was anticipated.

For example, in Kew, just 235 mm (9.25 inches) of rain was measured over that period, which was 43% of the average, meaning the amount of rainfall was comparable to a semi-arid climate.

In Devon and Dorset, some locations received no rainfall for 45 consecutive days through July and August, another United Kingdom record.

The lack of rain can be attributed to the high-pressure system over the United Kingdom at the time, which meant average pressure was 5 millibars above the expected for the summer months.

Additionally, death due to drought resulted in the loss of around 15% of the mature beech trees in the forest.

In contrast, the sessile oak did not suffer any death or growth suppression due to drought, but instead benefited from reduced competition with beech.

Sessile oak growth increased suddenly after the drought and remained unusually high until the 1990s, when beech recovered and regained dominance.

European Beech dominates temperate forests over large areas of Europe, but is considered to be particularly drought-sensitive and is predicted to be outcompeted by more drought-tolerant species in many regions as the climate warms.

The drought ended in October when a low-pressure system finally arrived to bring substantial rain to the United Kingdom.

This leads to wildfires which usually is the main impact of drought in the United Kingdom, with moorland vegetation such as heather badly affected as the peat bogs dry out.

The fourth and final stage involves drastic measures of water rationing to all businesses and homes in the United Kingdom in an emergency drought order.

[15] As of March 2019[update], according to the Environment Agency, due to projected population growth and the impact of climate change, England's anticipated demand for water will exceed its supply around the year 2045.