Minnesota (Fort Snelling) Weather for the year 1827
Mild Winter/Spring, Hot Late Summer –
Weather and weather-related events returned to a more benign mode for the Fort Snelling vicinity during 1827. Seasonable or above normal temperatures prevailed for virtually the whole year, annual mean temperature (46 F) up 2 F from 1826. Winter was the second mildest in eight years, and resumption of a new trend, destined to persist for the next eight years, the Mississippi opposite the Post experienced a March breakup. Late August/early September brought an unseasonably long spell of mid-summer-like heat, but frequent and heavy rains, like a year ago, occurred over much of September’s closing days.
Mild Winter – The ’26-’27 winter was the second mildest yet in the Post’s brief history, conditions over January and February generally sunny and thawing. January (mean temperature: 16 F) had afternoon temperatures in the 20’s and 30’s almost every day over the first two weeks, clear skies and light southwesterly winds the rule. An abrupt but temporary change came on the night of the 14th, as passage of a cold wave plunged the mercury from 30 F at 9PM to -6 F by 7AM of the 5th. Thanks to the “high” northwesterly winds prevailing on the latter, the mercury was still minus 6 F at 2PM. Temperatures would not to climb above zero again for another three days, the morning of the 17th bringing the winter’s lowest reading, -22 F. This proved to be only a brief lapse, though, as temperatures over the following days recovered to even milder levels than before the cold wave. Starting with the 22nd, the high 30’s to mid- 40’s were reached on five successive afternoons. February (mean temperature: 24 F) was also sunny, calm, and very mild. Twenty-one “clear” days were noted along with four snows and two rains. Conditions over the 14th-22nd were especially thawing, afternoons in the upper 30’s to the mid-40’s on each, several of the days above freezing in their entirety. The last few days of the month turned much more wintry, a “high wind snowstorm” blowing in on the 27th, the mercury in its wake dropping to -8 F on the 28th, coldest in nearly six weeks.
March Breakup of the Rivers – Spring was much less eventful than last year, with none of the deep snows, floods, or early heat. Early March (mean temperature for the month: 32 F) continued cold, -7 F recorded on the 2nd, but a strong southwesterly surge drove the mercury to 56 F on the 5th, morning and evening readings each holding in the 40’s. Following alternating freezing and thawing weather over the next twelve days, a steady mild pattern set in on the 18th. Afternoon temperatures through month end consistently reached the 40’s and 50’s, the highest (56 F) coming on the 24th. Nights were thawing or nearly so. The Mississippi cleared on the 25th, having been shut just 93 days this winter. April (mean temperature: 45 F), a relatively seasonable month overall, exhibited almost no upward trend in temperature from beginning to end. Rain fell on eleven days, eight of these over the twelve-day period the 8th-19th. Most afternoons were in the 40’s and low 50’s, the warmest a modest 65 F, lowest such extreme for an April until 1849. Compensating for the lack of balmy afternoons was the absence of many cold mornings, just two freezing at 7AM. May (mean temperature: 61 F) was sunnier and considerably warmer, 21 days clear and seven having rain. A gradual warming trend was displayed over the first twelve days, 86 F recorded on the 12th, a near record for so early, most subsequent afternoons in the upper 70’s and 80’s.
Warm Summer – Summer was generally above normal with a large number of warm nights, judging from 7AM temperatures (the latter of which, however, might have been inflated to at least some extent this particular season by 1) failure to read the thermometer at the prescribed time, 2) oblique angle sun exposure at 7AM, 3) or both). A long unseasonably late hot spell also covered late August and early September. June (mean temperature: 71 F), featured only a few 2PM observations as high as the mid-80’s, but numerous “7AM” readings in the 70’s and 80’s. Rainfall, distributed uniformly over the month, occurred on 13 days, and continuing the general circulation pattern of May, 21 days had south quarter winds. July (mean temperature: 73 F) was seasonably warm with somewhat less rainfall. Most of the nights, judging from 7AM temperature figures, continued warm, though only a few afternoons through the last week got as warm as 85 F. Conforming to the climatological “norm”, however, the warmest days of the month and summer occurred during the final seven days, afternoon temperatures reaching 96 F and 94 F on the 29th and 30th, respectively. In all, seven rains fell during the month, just two over the last thirteen days. Notes regarding Indian affairs appeared in the remarks column twice during July, one of these concerning an incident that was of some historical importance. From the 9th: “4 companies started on a expedition against the Winnebagoes”, this relating to the dispatching of troops to the [now] Winona area, scene of a June keelboat ambush which resulted in death of some crew members. Another entry, evidently unrelated to the trouble down the Mississippi, appeared on the 17th: “detachment moved for the falls [St. Anthony] to escort the Chipewa Indians in their return”. This was undoubtedly an operation to protect the Chippewa from their adversaries, the Sioux, one of the prime roles of the military here to keep the peace between these two tribes [Ziebarth and Omisky, 1970]. August (mean temperature: 70 F) was cloudy, rainy, and cool over first three weeks, but clear, dry, and unseasonably warm over the balance. Precipitation increased over the early days, “rain all night” falling on both the 1st and 2nd, the 8th having it all day. Only a few afternoons over the first three weeks got out of the 70’s, the 20th just 64 F at 2PM, “hoar frost” reported by Surgeon J. P. McMahon that morning. Diary notes on the 13th also reported the return of the original detachment sent against the Winnebagoes, the 17th noting “another detachment started for prairie du chien”. Despite the original expectations of trouble, the soldiers returned to Fort Snelling “not firing a shot” [Williams, 1881]. This premature taste of autumn was quickly followed by a long spell of unseasonably high temperatures. Behind clear skies and predominantly southerly winds, readings reached the 80’s almost daily from 22 August through month-end.
September Weather Contrasts – September (mean temperature: 61 F) brought a steep descent from the late heat to almost daily freezes near the close, separated by a long spell of frequent and occasionally heavy rains. Temperatures continued to trend upward over the first week, the mercury reaching 90 F on the 5th for the warmest temperature yet recorded so late in the season here. On the evening of the 9th, a two-hour-long aurora display was viewed, one that “beautifully illuminated … the NW quadrant of the heavens”. All-day showers on the 10th finally broke the long warm spell, first in a series of almost daily falls to come over the next two weeks. The 11th had “a gale from the northeast through the night [with] thunder & rain”, the 12th and 13th each brought “rain all day”, and the 15th/16th both had “rain all day & night”. Afternoon temperatures, having declined to the 60’s, recovered to the 80 F range on four straight days starting with the 17th, but the last nine were decidedly autumnal, a cold rain falling all of the 22nd with just 52 F at mid-afternoon. No 2PM readings higher than 56 F were registered on the remaining eight afternoons of the month. Frost was also noted on the mornings of the 23rd-26th as well as on the 30th. Some Observational Sleight-of-Hand. – Meteorological notes for October 1827 do not exist, Surgeon, J. McMahon, in a bit of subterfuge, submitting those from October 1826 instead. Evidently the ploy succeeded, but close inspection of the October “1827” register shows the columns to be unusually and neatly aligned, as if they were copied from another document in one sitting. October ’27 notes do exist, fortunately, for relatively nearby and climatologically similar Fort Howard (Green Bay), the month there being bright and sunny (23 “clear” days), with just one fall of rain. At Howard, the mercury hit 80 F on the 3rd, evidence that late September’s unseasonable coolness (assuming it had prevailed there), had given way in characteristic seasonal fashion to some balmy Indian Summer temperatures. Normal weather observing resumed at Fort Snelling in November (mean temperature: 32 F), the month featuring some nice Indian Summer weather early on. Afternoon temperatures mostly in the upper 50’s and low 60’s prevailed all the way through the 11th, just one cloudy day and no precipitation recorded. Cloudy, dull, and chillier weather set in after mid-month, the 18th-26th frequently sub-freezing day and night. On the 20th the St. Peter’s River froze, the Mississippi following on the 23rd. Both the latter morning and the 24th were only 3 F. The month closed mild again, three of the last four days reaching the mid-30’s to low 40’s.
Early Cold in December – December (mean temperature: 13 F) was reminiscent of the arctic-dominated ones early in this decade. Conditions remained mild through the 5th, near or just above freezing temperatures observed in the afternoons. But following a northeasterly gale with snow and falling temperatures on the morning of the 6th, a 16-day period of steady arctic cold took hold. Near or below zero temperatures were felt each day, as low as minus 14 F. A couple of snowstorms also occurred, one during the second week, the other on Christmas Day. History was made during December as the first regular mail service between Fort Snelling and Fort Crawford commenced over the Mississippi River ice, having been set up by Lt. Colonel Zachary Taylor of Fort Crawford, future 13th President of the United States [Hansen, 1958]. On the 3rd, according to the register, the “Mail started for La Prairie Du Chein”, and on the 24th, exactly three weeks later, it “arrived from Prairie Du Chein”. Taylor would be taking over command of Fort Snelling this coming spring.