Years run clockwise from 1940 at the top; radius is the selected series' temperature — a calendar month, or the average across each year. The faint line is the raw annual value, the bold one a trailing 10-year mean, and the dashed ring the series' mean across all years: outside it is warmer than average, inside cooler. The radial scale fits each series' own range, so the warming reads as the ring opening outward toward the recent years. "Average by year" covers 1940–2025 — 2026 stops in August, and a part-year mean is not comparable.