MOGREPS-G is the Met Office global ensemble: 18 members, four runs a day. Each run here is pooled with the one six hours before it, 36 members. Values are the model grid point nearest the city (about 20 km), not a station forecast.
On the meteogram the thin lines are the members, the colour band holds 10 to 90 % of them and the heavy line is the median. Tile rows are every six hours. The last rows give each local day: the median high and low with their 10–90 % range, and heating and cooling degree days (base 65 °F) against normal.
Normals are ERA5 1991–2020. On the map a dot is the median member's value for that day; “vs normal” is against the top or bottom of the mean daily curve.