Why this page exists
Web Mercator cannot show a pole. The projection runs to infinity at 85.05°, so no raster on the main map contains the North or South Pole at any size — not even on the globe view, which places its imagery in the same Mercator space. The Met Office global model carries values right to 90°, and this is where they are drawn.
Both caps are polar stereographic, true at 70°, rendered from the same global field as the main map — the same run, the same colours, the same numbers. The Arctic is oriented on the Greenwich meridian so Britain faces the reader across the bottom of the frame rather than sitting upside down at the top.
The pointer readout works here exactly as it does on the main map: the raster is a colour-mapped PNG drawn through a fixed palette, so sampling the pixel under the cursor and inverting it recovers the temperature. The coordinates beside it are the inverse projection, which agrees with pyproj to two micrometres.