Abstract
The year 1843 produced some unusually cold months in the upper Mississippi Valley, with March about 25°F below normal for the largest monthly departure of record in the area. A short summary of the winter months of 1842–43 in Wisconsin is included. A check of climatological data for Europe showed that unusually mild weather prevailed in eastern Europe during January and February 1843, while March 1843 was near normal. The effects of snow and ice cover in maintaining a strong and persistent anomalous flow pattern is alluded to. A high frequency of record coldest and warmest months in Wisconsin occurred during the 1830's and 1840's. High dust content of the upper atmosphere from frequent volcanic activity with reduced incoming solar radiation during the 1830's may be partially responsible for the occurrence of the many cold months.
