Some long‐term means from The Phenological Reports (1891–1948) of the Royal Meteorological Society

The Phenological Reports 1891–1948 of the Royal Meteorological Society are discussed; interpolated values in floral records have been re‐calculated, and 58‐yr district and British Isles weighted means, and annual differences from these, have been calculated for 11 flowering events. 20‐yr means and differences have been similarly calculated for a further 14 events, and the former approximately corrected to the 58‐yr means. For 11 main flowers in The Phenological Reports , the mean difference in flowering dates between south and north Britain was 21 days later for a distance of some 400 mi farther north. Extremes of earliness and lateness have been tabulated for the British Isles weighted means for these 11 flowers over the years 1891‐1948. Extreme earliness averaged 17‐7 days and extreme lateness 17‐1 days, but while extremes of earliness were fairly constant throughout the year or possibly became a little greater for summer than for spring flowers, extremes of lateness were much greater for spring than for late summer flowers. These differences are directionally in keeping with the finding of Hawke (1941) that in the winter months abnormally low temperatures are much more extreme than abnormally high values, while in summer the abnormally high values are more extreme than the exceptionally low. The standard deviations for the annual values of the British Isles weighted means are also given, and averaged 7‐0 days for the 11 main flowers.