In 1252, England experienced an intense period of heat and drought, as recorded by the Benedictine monk Matthew Paris in St Albans. He described "intolerable heat and drought" from March through July without relief from rain or dew. Similarly, the Chronicle of the Princes reported that the sun’s heat was so severe that the earth became excessively dry, preventing fruit from growing. The soil hardened to the point where it could not be ploughed for six weeks.

Episodes of extreme heat and drought were not uncommon during the medieval period, often causing significant agricultural challenges and health issues. Malaria outbreaks were noted in low-lying marshlands as stagnant water and warm conditions facilitated the spread of the disease. Fires also posed considerable risks during dry spells, highlighted by a major conflagration in Southwark, London, on July 10, 1212. Driven by high winds, the blaze rapidly engulfed the northern parts of the city, including timber-lined London Bridge, destroying vast areas, killing an estimated 3,000 people, and leaving many homeless.

Despite these hardships, the warm climate of the medieval period supported agricultural expansion and economic growth. Farming advanced into upland areas, and viticulture, introduced by Norman settlers, was significantly developed. This period of relative warmth, known as the Medieval Optimum, lasted from roughly the mid-10th to the mid-13th centuries. It coincided with population growth and a booming economy, which enabled the construction of many cathedrals and other significant structures.

This climatic phase was driven by increased solar radiation, a natural phenomenon that resulted in warmer temperatures over approximately 40 percent of the Earth’s surface. However, records derived from tree rings, glacier ice cores, and sediment layers indicate that global temperatures during the Medieval Optimum were still below current levels. The climate at that time was marked by considerable regional variability, differing markedly across various parts of the world.

In contrast, contemporary global warming involves rising temperatures across most of the planet and is occurring at a notably faster rate than during the medieval period. This distinction underscores the broader extent and speed of current climate change compared with historical climate fluctuations.