Methodology matters.

How the A–G grade is calculated

Infrastructure uses the highest available utility score: 4 points for a matched unplanned power cut or active water-supply interruption, 2 for another matched power record or active planned water maintenance, and 0 only when a usable water feed was checked with no qualifying event. A power feed without a verified postcode match does not establish zero disruption.

The nearest listed emergency department scores 0 below 5 km, 1 from 5 to under 10 km and 2 from 10 to 15 km. Distance is straight-line; opening, travel time and capacity are unknown. An active or active long-term TfL event within 5 km scores 1; a checked feed with none scores 0. TfL coverage is limited to Greater London.

Only when all three scoring inputs are available are their points added and capped at 6: A = 0, B = 1, C = 2, D = 3, E = 4, F = 5, G = 6. Missing or uncovered feeds are never converted to zero; without any one input, no A–G grade is shown. The report still gives a current-events summary and names the gaps. The grade is a current disruption signal, not an estimate of war, nuclear or overall personal risk.

Live sources and coverage

Met Office Weather Warnings are matched to the postcode centre across the UK. The direct NSWWS feed requires a Weather DataHub key. Without that key, the report uses the public Met Office/Esri mirror, updated about hourly; each report names the source used. A missing mirror warning cannot rule out a recently issued or changed warning, so check the current Met Office service. Weather warnings are separate from the A–G grade and from flood notices.

Power incidents are matched to full postcodes in the available UK Power Networks and Northern Powergrid feeds. Northern Ireland water incidents use NI Water’s affected-postcode listings. Road events use TfL data near London postcodes. The emergency-department directory includes Scotland and selected sites elsewhere; no listed site within 15 km is not proof that care is unavailable. Each live result shows its source and check time, or says why it could not be checked.

Environment Agency flood warnings and the nearest published river-level stage reading within 10 km are displayed separately for England. The station reading includes its measurement time and datum; it describes water at that station, not at an address. Neither result enters the A–G grade or represents long-term property flood risk. Other UK nations are linked to their official flooding services. Environment Agency API reference.

Data & Preparedness Score

This separate 0–6 score measures source availability, not risk. Reports add up to two points each for warning coverage, official guidance and data completeness. District reports use documented warning areas and historical records; full postcode reports use the live warning lookup and availability of coordinates, council density and settlement classification.

The two report types use different evidence, so read the breakdown before comparing them. An active warning or past flood does not deduct points.

Who maintains Doomsday Atlas

Doomsday Atlas team is the independent team that publishes and maintains the checker, district reports and preparedness guides. The site combines public data with editorial explanations of coverage, limitations and practical uses.

Population density comes from ONS mid-2025 estimates. Postcode locations come through Postcodes.io. Weather, terrain and live service sources are identified above and on individual reports.

During an emergency, follow instructions from the authorities responsible for your location. For a data question, consult the source linked on the relevant page. See the contact page for the team’s contact information.