As September settles into its middle weeks, the United Kingdom finds itself in a familiar meteorological in-between: warm enough to stir memories of summer, yet not quite warm enough to cross the threshold that science reserves for a heatwave. Temperatures across England and Wales will rise into the mid-20s Celsius this weekend and into Monday, carrying with them a muggy, summery quality that feels generous for early autumn. The warmth is real, but it is bounded — by rain in the north, by formal definitions that require sustained extremes, and by the quiet, inevitable advance of the season its