Minnesota (Fort Snelling area) weather for the year 1823
Temperature Extremes, Droughty Spells
Severe winter cold and intense summer heat, even more pronounced than that of 1821, highlighted Ft. St. Anthony’s weather during 1823. Precipitation falls during much of the year were also sporadic. Resurgent February cold helped produce the coldest winter here locally (December ‘22-February ‘23) for another 50 years. Summer (June-August), however, was the warmest for another fifteen. Except for a single wet spell in May, Spring was droughty, June and July also having infrequent falls of rain. Following a wet August, the scarce precipitation-day pattern set in again from mid-September on. Annual mean temperature for the fourth straight year was 43 F.
Mild January Interlude, Then More Cold – January (mean temperature: 12 F) brought a significant moderation in temperature, followed, however, by a bitter cold relapse in February, the result to be the coldest December-January period here locally until 1872-73. The New Year opened with the long arctic siege extending into its sixth almost uninterrupted week. Following a snowstorm on the 4th that left five inches, the mercury plunged to minus 28 F by next morning, “fresh” northwesterly winds predominating the day. This, however, marked the last of the long succession of arctic invasions for awhile, westerly winds bringing much milder air and a 42 F afternoon temperature by the 9th. No extended cold spells were felt over the rest of January, most afternoons reaching the 20’s. The snowpack received a six-inch replenishment on the 21st. Arctic domination resumed in February (mean temperature: 5 F), the first week possibly the coldest feeling one of the winter. Six of the first seven days had at least one thermometer reading in the -15 F to -22 F range, with “fresh” or “high” northerly winds noted. Another arctic blast brought -26 F and -22 F temperatures on the 14th and 15th, respectively, both days having “fresh” northerly winds. After nearly a month’s absence, thawing afternoon temperatures finally returned for a five-day run commencing on the 20th, the mercury reaching as high as 40 F, but a final arctic surge dropped the mercury to -22 F on the morning of the 27th.
Dry Spring – Spring featured mostly mild temperatures, and with the exception of mid-May, infrequent precipitation falls. Wintry weather lingered over the first week of March (mean temperature for the month: 30 F), a couple of mornings noted around zero, but following a 6-inch snowstorm on the 10th, the weather cleared off mild and sunny. Thawing temperatures occurred on each of the month’s remaining afternoons with no additional rain or snow recorded; highest was 53 F on the 28th. April (mean temperature: 48 F) continued mild and dry with many windy days. Only a few afternoons reached as high as the 70’s, the warmest 79 F on the 30th, but there were a number of unseasonably warm nights, thanks to relatively frequent southerly winds and cloudy skies. The St. Peter’s River was free of ice on the 3rd, the Mississippi on the 4th. A thundershower on the night of the 8th brought the first precipitation in 29 days, the rest of the month with just four mostly light falls. “Snow & hail” fell on the 21st. May (mean temperature: 56 F) was relatively cool with the spring’s only appreciable wet spell, over the middle part. Clear skies and “fresh” northwesterly winds prevailed over the first ten with just one fall of rain, a few mornings in the 30’s, but eight of the next eleven had rain, afternoon temperatures confined to the 50’s. A key event in Minnesota history occurred over this period when the first steamboat to reach to Post, the “Virginia”, docked at 5PM of the 14th. Aboard was Count Beltrami, the exiled Italian adventurer who would be seeking the source of the Mississippi during the coming summer. Excerpts from his diary describing the voyage upriver indicate some dry weather downstream as well, especially regarding the sighting of a forest fire, probably in the east-central Iowa area, which “raged for almost one entire night” [Ford and Johnson, 1961]. On 14 May, though, cloudy and rainy weather prevailed at Ft. St. Anthony with northeasterly winds and afternoon temperatures in the 50’s. The “Virginia” departed three days later at 4AM, also a predominantly cloudy day with rain, southeast winds, and a 7AM temperature of 48 F. Preview of things to come next month, skies cleared and temperatures began to heat up near the close, mid-80’s reached on two of the last three afternoons.
Hot, Dry June/July, Wet August – The Summer of ’23 provided the best example yet of the kind of protracted heat possible here, June and July each displaying many days in the 90’s and relatively few days with rain. Like its namesake of two years ago, the former brought a quick onset of hot weather, overall average temperature (73 F) equaling that of 1821. On the unseasonably early date of the 4th, the mercury reached 96 F at 2PM, first of thirteen 2PM observations at 90 F or higher during the month; at 9PM it was still 86 F. Then, on the 13th, the mercury hit 100 F, tying for hottest of the entire combined St. Anthony and Snelling era (1820-58); the temperature at 9PM also 86 F. Indicative of the month’s steady circulation pattern, prevailing winds blew from the south quarter on 23 days, rain falling on just six with no mention of anything heavy. Similarly hot and dry weather prevailed during July (mean temperature 75 F), eight afternoons at 90 F or above, twenty days having south quarter winds, and seven having rain. The heat was steadier and less spectacular than June’s, maximum temperature “only” 96 F. Another significant historical event occurred early in the month with the start of the Stephen Long expedition, the goals of which were to discover the source of the St. Peter’s river and explore the region along the northern boundary line of the United States [Jones, 1962]. Arriving at the Post on 2 July, the group spent the next week making final preparations. One member of the party, William H. Keating, took the opportunity to inspect the Ft. St. Anthony thermometer’s construction and placement. The instrument, exposed to the Southwest, was a glass tube attached to a brass plate with marked gradations. This type thermometer, which was reportedly supplied to all the military posts of the period, was manufactured by Mr. Fisher of Philadelphia, who was well regarded in the field. Keating found after performing some tests that the contamination effects of the sun’s rays on heating the brass back plate effect were ten degrees or more. Other posts Keating had visited had the instrument facing east, sometimes being protected from the sun, other times exposed [Ludlum, 1968]. An assessment of the Ft. St. Anthony’s placement with regards to sun contamination was not offered, but even allowing for this possibility, it appears that June and July 1823 were authentically hot months, given the many days with south quarter winds, “clear” weather, and few days with rain. The expedition left on 9 July, a day with “fresh” north-westerly winds, “clear” weather, and an 84 F 2PM temperature, reaching the source, Big Stone Lake, on 22 August. Another large body of water, Lake Traverse, lay just over a divide to the North, local Indians informing the party that during times of floods, the two lakes would join, permitting boats to be floated between the two [Jones, 1962]. Weather during August (mean temperature: 72 F) was considerably wetter and slightly cooler at Ft. St. Anthony, fourteen days having rain, five of them “heavy”, and just three afternoons in the nineties. A third key historical event this year was likely culminated in August, with the first successful “experiment” at private(?) wheat farming, by Lieutenant W. G. Camp, the Quarter-master, “a large quantity of wheat raised” near the Fort [Neill and Williams, 1881]. A generation from now, wheat would be far and away Minnesota’s number one export crop, heavy and frequent August rains such as these, however, generally hindering harvesting operations.
Fall/Early Winter Drought – The remaining months saw reestablishment of a new dry pattern, more protracted than before, but of likely slight impact given the season. Except for three “heavy” rainfalls over the first nine days, September (mean temperature: 56 F) was devoid of precipitation. Cool autumn-like temperatures quickly set in, the season’s first frost coming on the 7th, others following on the 12th, 19th, and starting with the 25th, on five successive mornings. Most afternoons over the last ten days didn’t reach higher than the 50’s. The dry pattern continued firmly entrenched during October (mean temperature: 47 F) with just two light falls of rain and snow each. Temperatures were occasionally quite mild, though, the first few afternoons back in the low 80’s, with many other days of Indian Summer weather. The temperature reached as high as 75 F on the late date of the 27th, but Halloween was subfreezing all day, with an inch of snow falling and ice seen running in the Mississippi. November (mean temperature: 31 F) was unusually clear and mild with changeable temperatures over several day intervals. Altogether there were 20 “clear” days, an unusually high figure for this climatologically cloudiest of the calendar months, and seven precipitation days. Six of these were snows (mostly “light”). Afternoon temperatures reached the 50’s again a couple of times over the first ten days, but mostly sub-freezing afternoons followed through mid-month. Probably due to its low stage, the St. Peter’s river froze on the 16th, opened in response to a several-day mild spell with temperatures in the 50’s and 60’s, then closed again for the season on the 28th. Anomalously cold weather predominated December (mean temperature: 13 F) for the fourth consecutive year. The first few afternoons were clear and mild, in the upper 30’s to mid-40’s with “fresh” southerly and southwesterly winds prevailing. But sharply colder weather followed on the night of the 3rd, the mercury near zero by the following 7AM, the Mississippi “closed with ice”. This initiated a 13-day arctic spell, most mornings in single figures or below zero, the majority of the afternoons in single digits or the teens. Following a thermal rebound to the 30’s on four straight days, a second more abbreviated cold snap dropped the mercury to -20 F on Christmas Eve, the month’s lowest temperature. A single light snow on the 8th was the month’s only recorded precipitation.