SMD comparison — surge years vs 2026

2026 shown against confirmed surge years 2018 and 2022, plus 2024 (no surge) and 2025 (confirmed surge). Dashed lines mark the 218mm and 320mm risk markers.

 
 
Soil moisture deficit — current position

Square 161 (SE England / Greater London area). Deciduous tree SMD* is the primary tracking metric for shrinkable clay subsidence risk.

 
Deciduous SMD vs trigger thresholds
 
 
 
218mm 320mm
 

* Soil moisture deficit (SMD) is a measure of how dry the soil is relative to its maximum water-holding capacity. A high SMD means the ground has lost significant moisture. In areas underlain by shrinkable clay, high SMD causes the clay to contract and crack — the principal mechanism behind subsidence damage to buildings and infrastructure.

† The 218mm and 320mm risk markers are Geobear-defined thresholds derived from analysis of historic subsidence case report data and previous surge years. They are not official Met Office or industry-standard figures. The 218mm level represents the SMD at which Geobear's historic data shows a material increase in subsidence activity on shrinkable clay soils; the 320mm level is associated with extreme and sustained surge conditions.

MORECS data — latest four weeks

Most recent four weeks of Square 161 data. Week-on-week SMD change shows the direction of travel.

Week ending Sun (hrs) Rain (mm) SMD grass SMD deciduous Wk change
 
⚠ Surge threshold effectively reached — 218mm marker just 2.8mm away

Sources: MORECS Square 161 week ending 16 Jun 2026; Met Office Red Extreme Heat Warning 17 Jun 2026; NOAA CPC El Niño Advisory 11 Jun 2026.

SMD deciduous reached 215.2mm in the week ending 16 June — just 2.8mm from the Geobear 218mm elevated-risk marker. At the same time, the Met Office has issued a Red Extreme Heat Warning for Wednesday 18 and Thursday 19 June, with temperatures forecast to reach 37°C in London on Wednesday and potentially higher on Thursday, with June’s all-time daily record temperature forecast to be broken. The 218mm elevated-risk marker will almost certainly be crossed in the next MORECS release (week ending 23 June). This is the moment this dashboard has been tracking since April. In the confirmed surge years of 2022 and 2025, the 218mm threshold was crossed in weeks 23 and 25 respectively. We are now in week 25.
Annual surge comparison
Year Profile First above 218mm First above 320mm Peak SMD Notes
2025 surge — called in advance

In May 2025, Geobear published an early-warning analysis identifying conditions consistent with a surge year — before the summer drying peaked. SMD crossed the 218mm elevated-risk threshold in Week 25 and the 320mm extreme threshold in Week 30. Geobear subsidence case reports rose by almost 200% between July and October 2025.

First trigger crossed
Week 25
Extreme trigger crossed
Week 30
Case report increase
+200%
Peak SMD 2025
332.4mm
ENSO / El Niño and NAO — forward watch

Sources: NOAA CPC El Niño Advisory (11 Jun 2026), WMO El Niño/La Niña Update (Jun 2026), ECMWF seasonal forecast (Jun 2026).

 
El Niño Advisory — NOAA CPC 11 Jun 2026. El Niño conditions now officially present.
NOAA CPC Advisory (11 Jun 2026): NOAA upgraded the ENSO status from Watch to El Niño Advisory on 11 June 2026 — El Niño conditions are now officially present. Sea surface temperatures are above average across the central and eastern Pacific Ocean, and atmospheric circulation anomalies are consistent with El Niño. CPC puts a 63% chance of a very strong event by November–January 2026–27, an event that “would rank among the largest in the historical record going back to 1950.” El Niño conditions are expected to strengthen into Northern Hemisphere winter 2026–27. The ECMWF is forecasting Niño 3.4 SSTs reaching +3°C by December.
North Atlantic Oscillation (NAO): The Met Office confirmed (3 Jun 2026) that the NAO shifted strongly into a positive phase at the start of June, strengthening the jet stream and driving the current unsettled, showery pattern. Critically, during May the NAO was predominantly negative — that blocking pattern is precisely what caused the heatwave that drove the +39.4mm SMD jump in a single week. The NAO is now acting as a temporary brake on SMD acceleration. Watch for any shift back toward negative NAO or Azores high blocking mid-to-late June, which would quickly restart drying conditions across southern England.
UK relevance: El Niño is a global context signal, not a direct UK trigger. However, a developing strong El Niño coinciding with blocking high pressure patterns and a dry spring significantly increases confidence in the surge-risk hypothesis.
Layer Role Current status
ENSO / El Niño Global context signal El Niño Advisory — officially present (11 Jun). 63% chance very strong event by Nov–Jan.
North Atlantic Oscillation Jet stream / blocking driver Easing from positive phase — high pressure rebuilding
UK pressure pattern Regional driver Red Extreme Heat Warning Wed–Thu. 37–38°C. June record forecast to be broken.
MORECS SMD Ground condition evidence 215.2mm — just 2.8mm from 218mm marker. Threshold effectively reached.
Case reports Impact validation 2025 confirmed +200% Jul–Oct. 2026 case report monitoring now active.
London 10-day forecast — subsidence drying lens

London used as a proxy for clay-rich South East England.

Loading live forecast…
 
Speculative weather signal watch

A surge-risk hypothesis strengthens only when multiple signals align and MORECS confirms ground drying.

 
Current assessment: all five signals are now at Concern or Strong Concern simultaneously for the first time in 2026. SMD is 2.8mm from the elevated-risk marker. El Niño is officially present and strengthening toward a potentially record-breaking event. A Red Extreme Heat Warning is active. The Met Office 3-month outlook signals hot conditions are more likely than normal this summer. The 218mm marker is expected to be confirmed crossed in next week’s MORECS release.

Learn more: What is subsidence?

Last updated:  ·  MORECS week ending:

Sources: MORECS Square 161 weekly data (Met Office Hadley Centre), Met Office UK weather summaries and ENSO commentary, NOAA Climate Prediction Center, WMO El Niño/La Niña Update (2 Jun 2026), Geobear internal subsidence case report trends.

This dashboard is an operational early-warning framework, not a property-level diagnosis. It should not be used as a basis for insurance or engineering decisions without professional assessment.

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