Here is an interesting chart and commentary:
Historical Correlation of the Dalton and Maunder Minima with Sunspot Activity The very cold temperatures from 1790 through 1830 are usually explained as being due to increased volcanic activity, including the Mount Tambora eruption of 1815 that caused the Year Without a Summer, 1816. However, low solar activity, with peak Sunspot counts of only 45 for Sunspot Cycles #5 and #6, is most likely the major cause. Even lower Sunspot counts (below 10) occurred during the earlier Maunder Minimum (1650 to 1700). These periods of Global Cooling were marked by crop failures that are inimicable to human life.