A reader of Dalton Minimum Returns asked a question that prompted this question: What were the temperatures at the beginning of the Dalton Minimum prior to the official start in 1790? I find this an interesting question as we maybe entering another climate phase similar to the Dalton Minimum real soon now.
Here is a plot of three sites in England from a paper by David Archibald:
Doing a little more research I found this paper published in the History of Meteorology.
Reconstruction of Late 18th Century Upper-air Circulation, Using Forensic Synoptic Analysis, Louis K. McNally, III
... the early 1780s in eastern Massachusetts, in general, exhibit shorter growing seasons, more winter days with fair-sky conditions, more summer days with thunderstorms, and more winter snowfall days than the remainder of the decade. Both shorter growing seasons and more winter days with fair-sky conditions indicate a prevalence of clearer Arctic or polar air masses in both summer and winter.
... in reconstruction of temperatures for Toronto, Ontario, Canada, found . . . 1783-1785 are all within 1° of the 50-year running mean.
... Tree ring chronologies for the western part of North America developed by Lough (1992)
show no large deviation from a long-term (1602-1960) mean.
... Ogilvie (1992) studied sea ice records for the area around Iceland and shows that on a
decadal scale the 1780s contained the greatest amount of sea ice on record. The series extends back to 1501.
... In the western United States, Fritts and Shao (1992) reconstructed temperature and
precipitation from a variety of spatial arrays of sites. These areas included the Columbia Basin, the California valleys, intermountain basins, southwest deserts, the northern high plains and the southern high plains. Throughout the entire area, temperature and precipitation data for the period from 1750 to 1800 show very little variation from the norm, with the exception of the temperature reconstruction for the high plains data set. There is a colder than normal period which stretches from 1770-1790 and it is found only in the high plains data set.