Learning About the Weather in Early Colonial New Zealand
When the first European settlers occupied the eastern South Island lowlands and hill country they had to learn for themselves about the area's weather, climate and hydrology. We traced 47 diaries and letter books written between 1835 and 1869, and found that most contained qualitative accounts of daily weather. The few meteorological measurements reported in them were usually low barometric pressures. For much of the South Island, settlers' observations are the only weather records available to us until the late 1860s, when a national network of meteorological observatories was in operation. Before informal weather reports can be used with any confidence, however, they must be validated. Accordingly, we analysed Joseph Munnings' qualitative accounts of the daily weather in Christchurch and its environs between November 1859 (when he arrived in the settlement) and late November 1866 (when his diary ends) and found (a) clear seasonal variations in temperature, precipitation, wind strength and direction, (b) evidence of cooling to 1861 them steady warming for the remainder of the period, (c) worsening drought after 1862, (d) severe winter snow storms in 1861, '62 and '63, then frequent dust storms, and (e) persistent, strong northwest winds inland and northeast winds near the ground with northwest winds aloft in Christchurch. We then compared his diary entries for three historically significant months with entries in contemporaneous accounts from other parts of the eastern South Island and found that independent observers had often noted the same or comparable wind direction and strength, type of precipitation, and stormy weather. In addition, the geographic spread of dates for the onset and end of an extreme weather event gave a realistic account of its passage across the eastern South Island. The findings reported here accord with the historical record, but provide greater detail about weather systems in the early colonial period. We conclude that despite their limitations, informal weather records, such as those in Munnings' diary, can be used to identify weather patterns and events for the period before meteorological measurements were widely recorded, and for areas far from meteorological observatories. We also show that information from runs of several years of continuous daily weather observations can indicate multi-year changes in the prevalence of particular weather systems, and suggest that the daily weather reports in Munnings' diary point to El Niño conditions in eastern South Island during the mid-1860s.