How this forecast is made
raindar is an independent UK rain page. We do not run a global weather model. We sample radar, a local forecast and an ensemble, and we give each a specific job.
This is not the Met Office, and it is not an official warning service. If the Met Office has issued a warning, treat that as the authority.
Right now
Whether it is raining comes from EUMETNET OPERA’s NIMBUS rain-rate composite: a 2 km European radar product, sampled at the native pixel plus a 3×3 neighbourhood around your place. The map is that same UK radar crop. Grey is coverage with no rain; the coastline shows through beyond radar range.
Temperature, wind and the sky summary next to that phrase come from the nearest MET Norway Locationforecast point, not from the radar.
Next two hours
The next-two-hours strip is a nowcast: we watch how rain on radar is moving and slide that field forwards.
Motion comes from OPERA CIRRUS (1 km reflectivity) using Lucas–Kanade optical-flow. Rain rate comes from NIMBUS. We issue a new 0–2 hour forecast on each new radar frame, on a 2 km grid, in five-minute steps.
It is a single extrapolation, not a multi-member STEPS ensemble, and it is not blended with a numerical weather model. Rain that grows or dies after the latest radar frame is exactly what this method cannot see, so skill falls with lead time. When radar coverage is too thin, we still show what we have, but we withhold timing phrases and alerts rather than invent them.
On some deploys the nowcast worker is off. Then the two-hour strip simply is not there.
Next day and this week
Amounts, temperatures and sky symbols for the next 24 hours and the week come from MET Norway Locationforecast — a point forecast based on ECMWF’s high-resolution model, taken at the nearest of our pre-swept ~0.1° grid points.
The wet-day line (Rain unlikely / possible / likely) is separate. That is ECMWF’s open ensemble (51 members, coarser ~0.25° grid) answering one question: how many members put at least 1 mm on that calendar day? When the ensemble also gives a typical amount, we show that as “most likely”, not as a second competing forecast.
MET Norway and ECMWF are related, not independent. We do not average them. MET Norway is the expected local amount, temperature and wind; hourly rain chance is MET Norway’s probability of precipitation; the ensemble is the wet-day likelihood and a typical daily total. When the two-hour nowcast is on, hourly rain bars in that window are left to the strip above rather than repeating the model.
Last six hours
Hourly totals come from OPERA NIMBUS accumulation. Where an Environment Agency rain gauge sits within 30 km, we show it as a cross-check. Those gauges cover England and Wales only — not Scotland, and not Northern Ireland.
Limits
Northern Ireland postcodes are district-level only (BT1), because there is no open unit-postcode source we can use. Radar and nowcast stay on OPERA’s native grid; MET Norway and ECMWF are sampled at their nearest cells, not downscaled onto the radar.
Coverage can be limited. Radar can be late. The two-hour forecast can be missing. When that happens the page says so rather than filling gaps with zeros.
Sources
Radar is EUMETNET OPERA via Open Radar Data, CC BY 4.0. Forecasts are MET Norway Locationforecast, CC BY 4.0. Nowcasts are built from OPERA radar, CC BY 4.0. The longer-range wet-day outlook is ECMWF open data, CC BY 4.0. Rain gauges are from the Environment Agency under the Open Government Licence v3.
Place names are GeoNames, CC BY 4.0. Great Britain postcodes contain OS data © Crown copyright and database right 2026, Royal Mail data © Royal Mail copyright and database right 2026, and National Statistics data © Crown copyright and database right 2026.
Who makes this
raindar is made by Tiago Espinha. It is an independent UK rain page, not a Met Office product, and not affiliated with, endorsed by, or part of any Dutch weather service.
The idea came from seven years living in the Netherlands, where rain nowcast apps — Buienradar and Buienalarm among them — were good at saying when a shower was about to arrive. That timing was more useful than a day-ahead total. raindar tries to give the UK something in that spirit, from open European radar and models, not from those apps.
Questions can go to info@raindar.co.uk. More at tiagoespinha.net.