Sun and Rain: The United Kingdom's Sunshine Against Its Rainfall at 1 km, 1961 to 2020

Sunshine and rainfall are the two numbers most people use to describe the weather of a place, but they are usually mapped one at a time. I map them together for every 1 km square of the United Kingdom, using the Met Office's HadUK-Grid thirty-year averages for 1961 to 1990 and 1991 to 2020, with a three by three bivariate colour scheme whose breaks are the terciles of the land. Across 245,077 squares, annual sunshine in 1991 to 2020 ranges from 784 hours on the summit of Ben Nevis to 1,992 hours at Dungeness, and rainfall from under 500 mm on the Isle of Sheppey to 4,796 mm at the head of Borrowdale. The two are strongly and negatively related (Spearman's rho = -0.72), so two corners of the bivariate scheme dominate: sunny and dry squares cover 21% of the land and dull and wet squares 24%, while sunny and wet squares (1.9%, mostly in Cornwall, Devon and south west Wales) and dull and dry squares (0.2%, around the Moray Firth) are rare. The towns of the sunny and dry third hold 49% of the population of UK towns of 15,000 or more. The sunniest 1% of squares lie overwhelmingly within 5 km of the sea. Between the two periods the UK became 5.6% sunnier and 7.2% wetter on average; 90% of the land became both. The brightening was largest in England (7.5%), especially the North East and East Midlands, and smallest in Northern Ireland. Gridded values rest on interpolation between stations and on changing instruments, so they describe broad patterns better than individual squares. An interactive version lets readers change the season, the breaks and the period, and look up any place. Interactive version: https://tristan-hotham.github.io/sun-and-rain-uk/. Data and code: https://github.com/Tristan-Hotham/sun-and-rain-uk. Blog post: https://blog.tristanhotham.com/2026/10/28/sun-and-rain-uk/. Contains Met Office data © Crown copyright 2026 and OS data © Crown copyright and database right 2026, Open Government Licence v3. The derived data files are released under the Open Government Licence v3; the paper and other material under CC BY 4.0; the code under MIT.