Minnesota weather for the year 1851

Forward Spring, Unseasonable September Heat (graphic)

Weather-related events were a bit less dramatic across the Territory in 1851 but the year still had its’ share of noteworthy features. Spring for the most part was very forward, July was warm and humid, and much of September had mid-summer-like heat. Annual mean temperature at Fort Snelling (46 F) was the second highest of the last 13 years, another year this mild in the mean not to be experienced until 1870. March and September were each the warmest calendar months of their names up to this time. Total precipitation at Fort Snelling for the year was a relatively modest 23 inches, though river stages over the Territory were high again for much of the boating season.

Mild, Dry Balance of the Winter – Very dry and mostly mild marked January and February’s weather at Fort Snelling. The “open-winter” pattern having resumed its sway after a one-year absence, very light snowfalls were experienced over the two months. Estimated snowfall at Snelling for the entire ’50’-’51 season was only about 12 inches, assuming an operationally sound snow gauge. January (mean temperature: 14 F) had mostly thawing afternoons over the first two weeks, a few reaching around 40 F, but a strong arctic outbreak swept in on the 16th, a day “with strong wind” and minus 9 F at 9PM. Next morning brought a frigid –24 F at sunrise, the afternoon reading just -10 F. The mercury was back to 31 F at 3PM of the 19th, but overnight a cold wave plunged it to minus 7 F by next sunrise. The very next day, the 21st, a brief but heavy thaw suddenly set in, 44 F noted at 3PM, 46 F at the same hour of the 23rd, but as the month approached its’ close, the winter’s most bitterly cold arctic blast brought -23 F on the morning of the 29th and -28 F on the 30th. February (mean temperature: 22 F) brought a pronounced warming over the first few days, the 3rd soaring to 49 F, the 4th hitting 50 F. Arctic weather was back on the morning of the 12th with -12 F at sunrise, the mercury already down to minus 10 by 9PM that evening, but overnight a strong southeasterly surge commenced a steep rise in temperature, 49 F read just 24 hours later at 9PM of the 13th, a rise of 59 F!; light rain was also recorded earlier during the day. The rest of the month had a more even day-to-day temperature pattern with a scattering of mornings just below zero and a few other afternoons near or in the 40’s. Showing the anticipation of an expected early spring, the Minnesota Pioneer reported on the 27th: “The mail came in Monday Evening [the 25th], everything indicates a breakup of winter, and we do not expect any more news”. This later statement was testimony to the fact that the Mississippi ice-highway was likely no longer safe for travel to the mail depots to the south.

Warm March & April, May Frost – Spring brought decidedly forward temperatures over both March and April, a familiar sequence of the past twenty years that would, however, be quite uncommon over the next twenty-five. March, according to the Pioneer, had “more fine days than anybody looked for”. Mean temperature at Snelling (40 F) was the highest for this month since records commenced, and the warmest in local climatic history until 1878. The first eight days were a bit chilly with afternoons no warmer than the 20’s. One-half inch of snow also came on the 8th, the month’s only such fall, though. A steady warming trend then ensued, mid-to-upper 50’s temperatures noted on the 10th-12th and mid-to-upper 60’s on the 13th-15th, including 69 F on the 14th — warmest ever so early in the season here. Light rain accompanied by “thunder and lightning” was also experienced on the 14th. On the 19th, ice was running in the Mississippi, both it and the St. Peters “open for navigation” on the 21st. A second even warmer surge brought 72 F on the 25th and 76 F on the 26th, 73 F also registered on the 29th. Just .11 inch of melted precipitation having fallen since 15 February, the 29th-30th brought some welcome moisture with 1.12 inches’ dropped over the two days. April (mean temperature: 49 F), notwithstanding a few fits and starts over the first half, was also well above normal. The first two days were cold and blustery, afternoon temperatures 45 F and 37 F, respectively, another inch of rain accompanied by gale-force winds received. Unseasonable warmth then returned, the afternoon of the 4th around 70 F, the first boat of the season having arrived at St. Paul that morning, but unpleasant conditions were back for the 8th and 9th with a half-inch of snow and sleet (melted) recorded. The 12th-13th brought an additional inch of cold rain, but thereafter a long two-week spell of beautiful warm, sunny, and dry weather set in. Nearly every afternoon at the Post reached the 70’s, with just one measurable rainfall recorded. The month’s warmest (79 F) came on the 18th, 76 F also noted for the 16th and 24th. Surgeon McClaren reported the appearance of “Violets and numerous prairie fires” on the 20th. Prelude to a cold opening of May, the last two days had afternoon temperatures barely reaching 40 F with light snow showers on each. May (mean temperature: 57 F) commenced frosty and almost winter-like, the 1st 29 F at daybreak, diary notes reporting “severe frost destroying early vegetation [overnight]”. At 2PM it was still only 37 F with force 4 northeasteries (25 miles per hour). Temperatures rapidly recovered to more seasonable levels over the ensuing days, daily ranges through the end of the third week generally in the 40’s for the mornings to the 70’s for the afternoons. A showery pattern also set in beginning with the 7th, fourteen of the remaining twenty-five days, inclusive, having falls. Total receipt at Fort Snelling for the month was 3.96 inches. Temperatures over the last ten days turned cool, afternoon readings mostly in 60’s, “slight frost” visiting on the night of the 22nd-23rd. Probably indicative of some significantly heavier falls in its upstream watershed, the St. Peter’s river reportedly overflowed its banks opposite the Post on the 29th.

Seasonable June and August, Warm July – Except for a hot and humid July, summer was generally pleasant in temperature, rainfall somewhat less than normal, at least in the Snelling vicinity. June (mean temperature: 66 F) had continued cool temperatures over the first few days. The night of the 3rd-4th brought another “slight frost”, the mercury 43 F at sunrise. Gradually warmer weather characterized the rest of the month, just several scattered afternoons, however, getting as warm as the mid-80’s. Less than a quarter-inch of rain fell at the Post over the first 17 days with local river levels “falling slowly”. But on the 9th high waters still overflowed “all the upper [steamboat] landing” at St. Paul, sawmilling operations remaining suspended. Regular rains resumed after midmonth, nearly 2 inches coming at Snelling before the close, local rivers rising rapidly over the last week. July (mean temperature: 75 F), like its predecessors of ’49 and ’50, was mostly warm and muggy, numerous Snelling sunrise temperatures noted in the 70’s. Warmest afternoon of the summer came on the 14th with 94 F at 3PM, three other days breaking the 90 F mark, all of these after the 20th. Most of the month’s 2.60 inches’ rainfall came over the second week, roughly 1 3/4 inches falling. August (mean temperature: 69 F) brought cooler and dry weather over the first half, just three afternoons as warm as 80 F, several in the mid-60’s or cooler; rainfall was just over a third of an inch. The 14th climbed to 89 F at 3PM for the month’s hottest, but the very next day it was just 59 F at the same hour, an extraordinary 24-hour plunge given the season. Prelude to a record warm September, the remaining days were warmer and wetter. Several afternoons over the last ten reached the mid-to-upper 80’s, the closing 16 days bringing nearly 3 inches’ rain.

Record Warm September, Mild/Dry October – September was exceptionally warm, mean temperature at Snelling (68 F) the highest for this month since records commenced. Some 3.64 inches’ rain was recorded, local river levels high virtually the whole month. The steamboat “Alexander Ramsey” resumed its service again between St. Anthony and Sauk Rapids after “once being laid up for low water”. The first ten days were like a mid-July warm spell, afternoon temperatures almost exclusively in the upper 80’s to low 90’s, nights holding in the upper 60’s to 70’s. A cold front finally broke the spell on the 13th, accompanied by heavy thundershowers that left 1.46 inches’ rain, but after a two-day spell of northerly winds and diurnal temperatures ranging from the 40’s to 60’s, another warm and humid spell began to build. Afternoons of the 18th-20th were each back in the low-to-mid 80’s, sunrise readings on the 19th, 20th, and 21st each in the upper 60’s to low 70’s. Following another cold front that left 1.35 inches’ rain over the 21st-22nd, autumnal weather finally took control. The morning of the 27th brought 34 F at sunrise, the season’s first frost visible on the Post grounds. October was mild and sunny with just three measurable precipitation-days, total fall 1.18 inches. Monthly mean temperature (51 F) was the highest since ’39, one of a number of unaccustomedly high October figures that would be recorded during this decade – a noteworthy feature of the 1850’s in addition to the cold Januarys. All the afternoons were either partly cloudy or clear and there were just a few cloudy mornings. Diurnal temperature ranges over the first twelve days were mostly in the 50’s for the mornings to the mid-to-upper 60’s for the afternoons, a few of the latter as warm as the mid-70’s. Reports of a successful 1851 crop season appeared in the Minnesota Pioneer on the 2nd: “All crops that were seasonably planted are now quite ripe, throughout Minnesota”. Cooler, crisper weather was the rule after mid-month, most afternoons in the 40’s and 50’s, mornings generally freezing or nearly so. Frost was reported at Snelling on the 14th, the “first ice” of the season observed on the 23rd with the temperature 20 F at sunrise. The “Pioneer” reported on the 15th that “cucumber vines are still fresh and bearing”. November was also relatively clear but more seasonable in mean temperature (30 F). Several light snows and a massive mid-month rainstorm comprised the month’s precipitation. Mild Indian Summer weather was felt on a few days over the first week, the mercury reaching the low 60’s on the 1st and the mid-50’s on the 5th. Few afternoons reached as warm as the 40’s thereafter, ice observed to be running in the Mississippi as early as the 9th. A 2.15 inch cold rain drenched the Post on the 13th, the rivers becoming free of ice again with “frost well out of the ground”, but the last ten days were subfreezing almost throughout, afternoon temperatures mostly in the 20’s and low 30’s. The morning of the 25th was 9 F at sunrise, the month’s coldest. The St. Peter’s and Mississippi rivers both closed for the season on the 30th. Continuing the trend of the last several years, December (mean temperature: 11 F) was cold and dry. Snow fell on four days to less than an inch. The first week featured a three-day thaw, the 6th reaching 46 F, but a 15-day arctic spell next descended over the area beginning with the 12th. Except for a two-day break with readings in the teens and 20’s on the 19th-20th, respectively, no temperature warmer than 7 F was read over the entire interval. Sunrise readings of –23 F and –22 F were noted on the 15th and 16th, respectively, the mercury on both days still just minus 16 F at 3PM, about 40 degrees below normal for mid-December at that hour!