GroundWater

The outlook for September is for river flows to be in the normal range across much of the UK, although the far south of England is likely to see above normal flows, mainly reflecting the influence of the exceptionally wet August in this area. Normal flows are the most likely outcome over the next three months. For groundwater, normal levels predominate in the southern Chalk, again partly reflecting the wet August, while below-normal levels persist in parts of north-east England. The three month outlook suggests mostly normal to below-normal groundwater levels.

July was an unsettled month and one of notable contrasts. Though temperatures cooled decisively thereafter, record‑breaking heatwave conditions characterised the 1st of the month. Following overnight temperature minima which exceeded 20°C in the south-east, Heathrow recorded 36.7°C, the warmest July day on record for the UK (in a series from 1853) and the hottest day in the UK since 2003. Throughout July, the north of the UK was generally wet and cool, whilst in southern areas conditions were predominantly dry although interspersed with intense downpours and thunderstorm activity.

The outlook for August is for normal to below normal flows across England and Wales, with an increased likelihood of below normal flows in some groundwater-fed catchments of southern and eastern England. For England and Wales, the outlook for the next three months is similar to that for August The outlook for Scotland is uncertain in the coming months but normal to above normal flows are most likely in the south and east and normal to below normal flows in the north. Groundwater levels are likely to be normal to below normal in August throughout the UK.

The outlook for July is for below normal flows across much of England and Wales, with the possibility of notably low flows in some areas. In north-western areas of the UK including north-west England, July is likely to see normal flows. This pattern is likely to persist over the next three months, although it is likely that river flows will return to normal across Wales. For groundwater, levels in July are most likely to be normal or below normal, and this is likely to continue over the next three months.

Overall, June was dry, especially in parts of south-east England, and sunnier than average. Monthly average temperatures were fairly typical for June but it was slightly warmer than average in the far south-east and there were some warm spells, with heatwave conditions developing through the final days and extending into early July. As expected for the time of year, soil moisture deficits (SMDs) climbed steeply and, correspondingly, the seasonal recession of river flows and groundwater levels continued, leading to some notably low late June river flows.

April was dominated by anticyclonic conditions and was, for most of the UK, largely dry, warm and sunny; the sunniest April on record (from 1929) for the UK. The fine spring weather was bookended by cool and unsettled spells in the first and final weeks, and north-western areas experienced a stormy interlude mid-month. Overall however, April was warmer than average and saw some very warm spells. With climbing evapotranspiration rates, and much of southern Britain receiving little appreciable rainfall, soil moisture deficits (SMDs) increased markedly above the late April average.

The outlook for May suggests normal river flows are likely in northern Britain, and normal to below-normal flows further south. This reflects the notably low April rainfall across England and Wales, with less than half the monthly average received in most areas; however, early May has been very wet in all regions, which decreases the likelihood of very low flows and increases the chances of above-normal flows in the north. The groundwater outlook is for a similar picture to April, with mostly normal and below-normal levels.

Considered at the national scale, weather conditions in February (although exceptionally sunny) were typical of the late winter but the spatial and temporal variations in rainfall amounts were substantial – reflecting the preferred paths taken by the rain-bearing frontal systems. Generally river flows continued their late January recessions during early February with frozen catchments contributing to relatively depressed flow rates.

November was a damp and dull month, the dullest November since 2004 for the UK. Temperatures were mild for the time of year, particularly during the first half of the month, contributing to mean January-November temperatures that rank 2014 as the warmest on record for the Central England Temperature series back to 1659.

The Hydrological Summary is available here.