Data: ERA5 reanalysis via Open-Meteo, taken at the nearest model grid point to the postcode — not a Met Office station record. Baselines are the mean of the same calendar months over up to the previous 10 years at this location (the years actually used and the data coverage are stated with the result; missing values are excluded, not counted as zero). Whether conditions meet a contractual test (e.g. JCT “exceptionally adverse weather” or an NEC 1-in-10-year event) is a matter for the contract — this is a factual weather record, not advice.