Research and analysis

Lincolnshire and Northamptonshire water situation: December 2025 summary

Updated 14 January 2026

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

Following an exceptionally wet November, rainfall continued into December, and the Lincolnshire and Northamptonshire Area (LNA) ended the month with a total rainfall of 74 mm (128% of the long term average – LTA), classified as above normal for the time of year. The majority of rainfall fell during the first half of the month, resulting in a comparatively dry end to December.

Consequently, soil moisture deficit (SMD) and river flows responded to the wet conditions but declined towards the end of the month. Monthly mean river flows at our indicator sites recorded above normal to notably high flows for December; however, by month-end, most sites had fallen back into the normal flow category. Groundwater levels continued to rise throughout December, with all monitored sites classed as above normal to exceptionally high by the end of the month. Reservoir stocks across the area generally increased over the month, although the majority of sites remained below their normal operating curves.

1. Rainfall

After record rainfall across LNA during November, December was less extreme but still recorded above normal rainfall across the area, totalling 74mm (128% LTA), with the majority falling during the first half of the month. Rainfall during the second half of December was comparatively limited, with around 5mm recorded after 18 December.

There was a slight north-south split across the 6 hydrological catchments within LNA. The 2 most southern catchments, the Upper and Lower Welland and the Nene, received normal rainfall totals, while the remaining 4 catchments recorded above normal rainfall, ranging between 130% and 144% of their respective LTAs.

The unprecedented rainfall in November resulted in the final 3 months of 2025 being the 12th wettest October to December period on record for LNA, with rainfall totalling 182% LTA. The 3 northernmost hydrological catchments experienced exceptionally high rainfall over this period. The Louth, Grimsby and Ancholme and Witham to Chapel Hill recorded the sixth highest totals on record, whilst the Steeping, Great Eau and Long recorded the ninth highest. All 6 hydrological areas saw rainfall exceeding 127% of their respective LTA for the period.

Rainfall during the second half of 2025 was above normal across LNA, at 112% LTA, with 4 hydrological catchments recording above normal totals and notably high rainfall in the Louth, Grimsby and Ancholme. However, when considering 2025 as a whole, the influence of the dry start to the year is evident. LNA received 90% LTA rainfall, with catchment totals ranging between 83% and 99% LTA, despite the high rainfall observed during the final 3 months of the year. Five of the six hydrological catchments recorded Normal rainfall totals for 2025, while the Upper Welland and the Nene experienced Below Normal rainfall.

2. Soil moisture deficit and recharge

SMD continued to reduce in response to the above normal rainfall observed in December. The SMD across LNA by the end of the November was 21mm; however, this had reduced further to 10mm by the end of December, and had been lower during the month at 7mm.

The rainfall over the past 2 months has seen a significant reduction in the SMD across the area, with it dropping 96mm from the end of October when the deficit was 106mm. Across the 6 hydrological catchments there is an east-west split in SMD, with catchments in the west having an SMD equal to or below 10mm, while the eastern catchments had an SMD between 11mm and 40mm. Four of the six hydrological catchments have an SMD between 6mm and 25mm less than the LTA, while the SMD in the Steeping Great Eau and Long and Upper Welland and Nene was between 5mm above and 5mm below the LTA.

3. River flows

Mean monthly flows ranged from 125% to 314% LTA, with classifications ranging from above normal to exceptionally high. Of the sites monitored, 4 moved from above normal or notably high classifications in November to exceptionally high in December. The River Welland at Ashley recorded its highest monthly mean flow on record, with an average flow of 8.16 cubic meters per second.

By the end of the month, following a drier second half, daily mean flows at all sites had fallen back into the Normal banding, with the exception of the River Lud in the Chalk, which ended December with above normal daily mean flows.

4. Groundwater levels   

Following the recent rainfall, recharge was significant during December and groundwater levels across all aquifers continued to rise through the month. All monitoring sites with data ended December at above normal to exceptionally high levels. Grainsby, in the Chalk, showed a marked recovery, having moved from below normal at the end of November to above normal by the end of December.

5. Reservoir stocks

Although reservoir stocks were generally below target at month-end, all sites are now back above drought-alert levels. Ravensthorpe and Hollowell rose from below their operating curves earlier in the month to finish well above their normal operating levels.

6. Environmental impact 

During December, there were 25 flood alerts and one flood warning issued. All transfer schemes remained off throughout December. No licence cessations were issued.

7. Forward look

7.1 Probabilistic ensemble projections for river flows at key sites

March 2026: Flows on the Nene are projected to be broadly in line with the expected probability. North Brook shows an increased likelihood of normal flow conditions. Moving north, Louth Weir on the River Lud and Tattershall Bain suggest a greater likelihood of normal or above normal flows. In contrast, Witham at Claypole indicates an increased likelihood of Below normal flows.

June 2026:  Flows on the Nene and North Brook are generally in line with the expected probability, with a slightly increased likelihood of greater than Normal flows. The northern sites are showing an increased chance of Normal follows, with Tattershall Bain suggesting a greater probability of higher flows.

7.2 Probabilistic ensemble projections for groundwater levels in key aquifers

March 2026: All sites are showing an increased probability of groundwater levels being normal or higher with none of the modelled rainfall scenarios showing exceptionally low levels.

September 2026: Almost all sites are showing an increased probability of groundwater levels being normal or higher. Grainsby suggests an increased likelihood of below normal levels.

Author: Pan Hydrology Team, Hydrology-EAN-and-LNA@environment-agency.gov.uk

All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report

Contact Details: 03708 506 506