Minnesota (Fort Snelling) weather for the year 1833

More Relative Warmth & Dryness

The above normal temperature/infrequent precipitation pattern continued over much of 1833 at Fort Snelling. Annual mean temperature was up to 47 F, tying the highest-to-date figures of 1825 and 1830, and growing season precipitation counts were again low. Winter was the mildest thus far in fourteen years, and early spring, like a year ago, provided unaccustomed forward warmth. July brought a long hot and humid spell, the closing four months, excluding October, even milder than a year ago. The freeze-up of the Mississippi was delayed until after Christmas.

The Mildest Winter Yet – Continuing December’s mild pattern, the opening seven weeks of 1833 featured almost uninterrupted unseasonable warmth, December-February mean temperature (22 F) the highest such (winter) mark of the Snelling era (1820-58), and the highest here locally until 1877-78. In addition to its relative unhealthiness, the frequent thawing and damp weather must have made back and forth travel over the Mississippi ice highway to Fort Crawford treacherous much of the time. January, like December, was very “cloudy” with many thawing days, average temperature (20 F) surpassing 1824’s previous high figure by 3 F. During the first week an unprecedented for this time of year four-day spell of continuously melting temperatures and daily rains set in, the 2nd-5th in the mid-30’s to low 40’s night and day. A brief arctic spell followed, the mercury plunging to -17 F on the 10th, but after a few additional subzero mornings over the next week, the mild/cloudy regime resumed control. Nine of the last fourteen afternoons were in the 30’s and 40’s again, the 21st registering 45 F. February (mean temperature: 20 F) was also very mild with light precipitation, the first three weeks particularly unseasonable. Afternoon temperatures reached 32 F or above 14 times over this stretch, several days continuously thawing or nearly so, 47 F readings registered three times. Entering the last week, it must have seemed that winter as it was usually known here had been largely escaped this season. But in a surprising turnabout, an eight-day arctic spell suddenly enveloped the area starting with the 23rd. Below zero cold was felt each morning through the 2nd of March, lowest temperature of the whole winter, -20 F, recorded on this latter day. Such a distinction for a March would not to be repeated until the winter of 1864-1865.

Mild Spring Also – Spring was much like last year with unseasonably warm temperatures in March and April together with infrequent precipitation falls. Conditions rapidly warmed over the early days of March after the late arctic surge, mean temperature for the month (33 F) finishing several degrees above normal. Record premature warmth came on the 18th with 70 F at 2PM, highest reading ever recorded so early in the season by nearly two weeks. Adding to the mid-spring flavor, five rains in eight days occurred over the 16th-23rd. The Mississippi cleared of ice on the 24th. Another spell of unseasonably mild air brought 64 F and 68 F, respectively, on the 30th and 31st. April (mean temperature: 51 F) was also much warmer than normal but not quite to the extent as 1832. Six days recorded precipitation, five of these rains. Eighteen days were designated as “fair”. Temperatures through the middle of the second week continued quite mild, afternoon temperatures in the mid-50’s to upper 60’s, “thunder and rain” occurring on one day. Conditions then relapsed temporarily, snow observed on the 11th, but much warmer weather followed, the 20th hitting 78 F and the 27th 80 F. May (mean temperature: 60 F) brought continued above normal warmth over its greater portion. General weather was bright and sunny, 22 “fair” days recorded with eight rains. On the 5th and 16th, the mercury soared to 86 F. The month’s coolest weather came over the last week, the 26th decidedly unpleasant with northeast winds, rains, and falling temperatures (57 F, 50 F, and 42 F at the official times). The following morning was 43 F at 7AM.

Prolonged July Heat, Two “rare” Rainy Spells – Summer ’33 featured a two-week oppressive period covering late July along with a couple of minor rainy spells. Generally seasonable temperatures prevailed during June (mean temperature: 67 F), total rain-day count (eight) the highest for a summer month since 1828. The opening days continued late May’s backwardness, the 1st noted as: “rain – cool & windy” with 42 F, 54 F, and 42 F readings at 7AM, 2PM, and 9PM. The 2nd was “cloudy” with a 40 F to 63 F range. A slow warming then developed, warm and muggy weather resident by early of the second week with 86 F to 89 F readings noted on three successive afternoons. Six rains fell over the eight-day period the 11th-18th, afternoon readings on some days failing to reach 70 F, but sunnier, drier weather closed the month, the last twelve days rainless. Another three-day spell of warm weather also occurred near the close, each of the afternoons near 90 F. July (mean temperature: 73 F) presented a cool first half but a very warm second. Twenty-three “fair” days were recorded, rain falling on eight. Most afternoons over the first two weeks were confined to the 70’s, ten days having prevailing winds out of the north quarter, an unusual preponderance for this time of year. On the 14th, following four straight days of prevailing northwesterlies, an “atmosphere smoky” entry was noted, possibly relating to distant prairie or forest fires in that direction. A long warm and muggy spell then set in, afternoon temperatures over the 16th-28th reaching the upper 80’s to low 90’s almost daily, the 18th hitting 94 F. August (monthly mean: 70 F) was sunny with few uncomfortably warm days, the warmest (86 F) occurring three times after mid-month. Twenty “fair” days were tallied, six having rain. Four of the latter came during the second week.

A String of Monthly Mean Temperature Anomalies – The remaining four months brought an unbroken run of pronounced monthly mean temperature anomalies: the warmest September to date (a tie with 1825), the coldest October, the second warmest November, and the warmest December. September (mean temperature: 62 F) featured a large number of mild days and nights with summer-like warmth. Just one afternoon was observed as warm as 80 F, that being 81 F on the 2nd, but eighteen mornings had 7AM readings in the 60’s, several over the last week. Eighteen “fair” days were noted along with six rain-days, a “slight” frost occurring on the 11th. October (mean temperature: 41 F) was the coldest thus far in fifteen years, numerous crisp days and frosty nights experienced. Twenty days were “fair”, four having rain and three snow. Warmest temperature was just 62 F, on the 8th, lowest such October figure in the Twin Cities vicinity until 1925. An early taste of winter arrived on the 16th, snow commencing at 8PM, continuing into the next day while the temperature hovered around freezing. Another later cold outbreak on the 28th kept the mercury subfreezing all day, ice seen running in the Mississippi on the 29th. November (mean temperature: 37 F), just four degrees colder than October, was the second mildest in 15 years. Conditions were much like October, with many days of fine weather. Altogether there were 20 “fair” days, two rains, and one snow noted in the diary. Most afternoons over the first half were in the 40’s and 50’s, the month’s first freezing temperatures not coming until the 12th. During the early hours of the 13th, an unusually spectacular display of the annual Leonid Meteoric Shower was witnessed by new resident Surgeon N. S. Jarvis. As he wrote in the diary: “Meteoric or shooting stars were seen early in the morning and continued flying in every direction until daylight. They were extremely brilliant and very much alarmed the Indians”. Temperatures over the ensuing days declined a bit, most afternoons in the 30’s to low 40’s, one morning dropping into the mid-teens, but a warming trend closed the month, the 26th 47 F, the 28th 54 F with “fair” skies and light southwesterly winds. December was exceptionally mild and “cloudy”, month mean temperature (31 F) breaking 1832’s mark by six degrees F. Conditions over the first half were very reminiscent of November 1830 with day after day of monotonous overcast and unseasonable mildness. “Cloudy” weather predominated each of the first sixteen, daily temperature ranges almost unvaryingly in the mid-30’s to low 40’s, and as high as 45 F. Not a single subfreezing temperature was noted until past mid-month, the Mississippi reportedly “free from ice” on the 13th. Sunnier but still mild weather predominated through Christmas, the season’s first arctic air intrusion finally pushing in on the 26th, minus 3 reported on the 27th. The Mississippi was finally “frozen” on the 29th, nine days later than 1826’s late closing date record (assuming this was the first freezing-over day). Following snows on this day and the next, New Year’s Eve saw an incipient rush of extremely bitter arctic air, the mercury 4 F at 2PM, minus 11 at 9PM.