Minnesota (Fort Snelling) weather for the year 1835

Unseasonably Cool after Mid-Year 

The ten-year run of almost exclusively warmer than average years came to an end with 1835, a year full of interesting weather events and spells. Historical climatologists regard 1835 and 1836 as years that felt the cooling effects of a volcanic dustveil [Ludlum, 1985], the likely culprit being the eruption of Nicaragua’s Mt. Coseguina in February ’35 [Bradley & Jones, 1992]. At Fort Snelling, January to May alternated between anomalous warmth and cold, a decidedly coolish pattern clearly established after mid-June. Summer was the coolest and most rain-frequent in sixteen years’ history, September, October, and November each with periods as cold as had been ever known so early in the season. Annual mean temperature was down to 43 F.

Mild/Cloudy January, Extreme Early February Cold – January and February, like a year ago, were a study in thermal contrasts, in opposite anomaly sequence, however. The former (mean temperature: 23 F) was the mildest thus far in sixteen years’ history, the latter 14 degrees colder with a memorable arctic blast early on. The opening days of new year brought some frigid temperatures, minus 16 F noted for both the 3rd and 4th at 7AM, but beginning with the 7th, a drawn out, unseasonably mild/overcast pattern not unlike November 1830 and December 1833 took hold. Nineteen of the next twenty-six days, inclusive, would have thawing temperatures at least some of the time, and twenty-three of these would be “cloudy”. On the 11th the mercury climbed to 44 F for the month’s highest temperature. February’s opening days brought sharply colder temperatures, subzero readings noted for each of the observation times on the 2nd and 3rd, including 16 below at 7AM on the latter, but this was only a prelude, as following a modest warming to the mid-teens on the afternoon of the 5th, an even more powerful arctic blast swept through overnight. The 6th would be one of the coldest feeling days in Post history, the mercury –18 F at 7AM, –16 F at 2PM, and –22 F at 9PM, coupled with “high” northerly winds. Next morning, the 7th, brought minus 30 F at 7AM, tieing the record cold February mark set three years ago. Temperatures recovered dramatically over the ensuing days as the core of the frigid air mass spread rapidly south and southeastward, destined to produce some frigid weather of historical proportions in those parts of the country. At Snelling on the 12th, the mercury hit 49 F with rain noted. The next eleven days featured large temperature fluctuations, a few mornings with subzero temperatures, a few other afternoons in the low 40’s, but on the 24th, the month’s second strong cold wave, a quite unusual occurrence climatologically, accompanied by “heavy wind and snow squalls”, plummeted the mercury from 40 F at 7AM to 0 F by 9PM. In the front’s wake, minus 17 F and minus 18 readings were recorded for the mornings of the 25th and 28th, respectively.

Mild March, Cold April, Warm May – Lingering arctic cold opened March, the first five mornings each in the -2 F to -9 F range, a couple of afternoons confined to the mid-teens. But in rather abrupt fashion, a steady mild pattern next took over, most of month’s remaining afternoons to reach the 40’s and 50’s, with not a single 7AM reading lower than 21 F. Three snows and rains, each, were noted along the way. On the 30th, the mercury rose to 62 F, the ice in both the Mississippi and St. Peter’s breaking up opposite the Post to make this the ninth (likely) consecutive March event. In spite of the cold start, March’s mean temperature (33 F) finished several degrees above average. April, however, had its’ share of cool and blustery weather. Mean temperature (44 F) was 6 F colder than the average of last five Aprils, six days having rain, three with snow, and three with hail. The early part was forward enough, five of the first ten days in the upper 60’s to the 70’s, 77 F registered on the 9th. Conditions then deteriorated drastically, afternoon readings of just 31 F noted for the 12th and 13th, along with observations of “high” west to northwesterly winds for the days. The 14th brought an inch of snow, and the 16th was just 31 F again at 2PM. Mostly cloudy weather with afternoon 40’s and 50’s predominated through the close, mild temperatures returning on the 30th, with 71 F at 2PM – the highest in three weeks. May (mean temperature: 61 F) provided regular rains (eleven falls) and, after mid-month, steady above average temperatures. The first half was more variable, the 2nd climbing to 81 F for season’s warmest so far. The 7th, however, was chilly and wet with “rain during the whole day”, northeasterly winds, and a 46 F temperature at 2PM. Summery weather comprised most of the balance, afternoons generally in the mid-70’s to low 80’s, a number of showers and occasional thunderstorms occurring.

Cool, Wet Summer – Summer ’35 was the coolest and most rain-frequent in sixteen years’ history up to this point, average June-August temperature (68 F) about 1 F lower than 1820’s, total rain-day count (36) surpassing last year’s mark by two. Early June (mean temperature for the month: 67 F) brought additional premature warmth, upper 70’s to low 80’s experienced over the first week, a four-day spell over the second producing mid-to-upper 80’s readings. Seven rains in ten days came over the 3rd-12th, and following heavy showers on the evening of the 12th, much cooler weather set in, nearly all of the rest of the afternoons confined to the 60’s to mid-70’s. Cool temperatures persisted over much of July as well, monthly mean temperature (69 F) equaling 1820’s low figure, nine days recording rain. Just a few afternoons over the first three weeks got as warm as 80 F, four days out of five over the 6th-10th confined to the 60’s, very unusual for July. The only semblance of a warm spell came over the 23rd-29th, five afternoons reaching the mid-80’s to low 90’s, the summer’s maximum (92 F) coming on the 23rd. August (mean temperature: 68 F), like June, was relatively warm over the first half, unseasonably cool over the second. Thirteen days had rain. Temperatures reached the mid-to-upper 80’s daily for a week straight beginning with the 5th, “fair” skies and south to southwesterly winds the rule, but after the 16th conditions turned very cool and rainy. Average 2PM temperature for the last fifteen days was just 67 F, with nine rains noted.

Early Autumnal Cold and Snows – Fall was easily the decade’s most unpleasant thus far, unseasonable cold prevailing over much of September and November, an unseasonably early six-inch snowstorm coming in October. September (mean temperature: 55 F) tied 1831 and 1826 as the coolest in sixteen years. Temperatures through the 10th were a bit warmer than late August’s, several afternoons reaching the mid-70’s and a couple of nights remaining in the 60’s. But mid-autumn-like chilliness ensued, only two additional afternoons through the close as warm as 70 F, more than half in the 50’s. A few others were only in the upper 40’s. The 20th brought the season’s first frost, a day “cold with high [northwesterly] wind” (2PM temperature: 50 F). Additional visitations came on the next three mornings with the 23rd’s “heavy”. October (mean temperature: 46 F) brought a varied assortment of weather. Chilly conditions continued over the first week, the 3rd through 6th each “cloudy” with northwesterly winds and afternoons in the 40’s. Starting with the 8th, however, a delightful week-long spell of Indian Summer weather set in, afternoon readings reaching the 70’s on five consecutive days over the 10th-14th. Such a welcome change prompted Surgeon N. S. Jarvis to note on the 11th: “weather remarkably mild”, this being a day with “fair” skies, southerly winds, and a 2PM temperature of 76 F. No rain having fallen since September 18th, the “prairies commenced burning” on the 10th, and an “atmosphere smoky” entry was noted for the 12th. Signs of a major change appeared on the 14th, though, as thunderstorms brought the first rains in 26 days, the next three having falls as well. Late on the 20th, the “wind suddenly changed during the night to northwest accompanied by snow”, and temperatures plummeted to the mid-20’s by morning. On the 22nd, a six-inch snowstorm, second only in earliness and depth to October 1820’s great storm, buried the Post, creating a wintry landscape that likely persisted for a couple of days. A mild and damp pattern next set in, four successive days over the 25th-28th experiencing mist, fog, and occasional rain; the 27th reached 55 F at 2PM. November (mean temperature: 24 F) was the coldest yet in Post history. A last taste of Indian Summer weather opened the month, afternoon temperatures over the first three days at or near 60 F, the 7th with showers during the day and a 52 F reading noted at 2PM. Rapid deterioration followed, another six-inch snowstorm blanketing the Post on the 10th, the mercury observed no higher than 25 F on the 15th. Temperatures recovered to the mid-40’s on the 17th, and that evening a spectacular prairie fire/aurora scene was captured in words by Surgeon N. S. Jarvis: “On the night of the 17th at 10 o’clock the sky was illuminated by a beautiful display of the Aurora Borealis. Broad sheets of light shot forth from the zenith in every direction — like radii from a centre to the very verge of the horizon. To increase the beauty of the spectacle — large black clouds — in different parts of the horizon were illuminated by the reflection of the burning prairies — which they imparted to these a deep orange color and gradually changing as the atmosphere became clear to a brilliantly phosphorescent light. These phenomena lasted for nearly two hours”. Much colder weather then descended on the area, the month’s final two weeks January-like with mornings generally in single figures or subzero, afternoons recovering to just the teens. On the 21st, the Mississippi froze over for the winter, -10 F and -11 F temperatures read on the 22nd and 29th, respectively.

Sunny, Dry December – December (mean temperature: 16 F) brought a return to relative thermal normalcy, but with an unusual amount of sunshine and no recorded snows. Twenty-four days were “fair”, two rains being the only recorded precipitation. Unseasonable cold continued into the first week, minus 12 recorded on the 1st, several other mornings below zero or close to it. The 8th, however, reached 34 F, just the second thawing day of the last three weeks, the 13th hitting 42 F and the 13th 40 F. On the latter, rain reportedly fell “in the forenoon and during the previous night”. A cold wave brought -10 F temperatures on the 21st and 22nd, but the last week was relatively mild again, several afternoons in the upper 30’s to low 40’s.