Minnesota (Fort Snelling) weather for the year 1830
Continued Dry with an Oppressive July, and Very Mild October-November
The dry pattern held sway at Fort Snelling over most of 1830, accompanied by some notable periods of unseasonably warm temperatures. Precipitation frequencies during both winter and summer were especially low, and mean temperature for the year (47 F) tied 1825’s figure as the highest thus far in eleven years’ history. July would be the hottest calendar month locally until 1936, and October/November were each exceptionally mild. December, however, brought deep snows and record early intense cold.
Another Dry Winter – Continuing its predominance of local weather patterns, the old decade’s closing dry regime extended through the opening months of the new. January and February 1830 were almost snowless with the Mississippi showing a very low stage at breakup time in March. January (mean temperature: 12 F) had 25 “clear” days and just four with snow. Daily temperatures through the third week were quite variable, roughly half the afternoons near or above freezing, as warm as 47 F on the 14th. A few other mornings, though, had subzero cold, the 10th recording minus 10. Steady arctic weather ruled the remaining days, most afternoons no warmer than single figures, nearly all the mornings near or below zero. More mild and bright weather characterized February (mean temperature: 23 F), 21 “clear” days recorded along with just three snows. Bitter cold persisted over the first week, with -20 F read on the 6th, the winter’s coldest, but this was followed by an abrupt spectacular warming, the 8th through 19th providing the balmiest succession of winter days yet known here, nine of the afternoons in the 40’s and 50’s. On both the 9th and 13th, the mercury soared to 54 F, the 14th even higher at 57 F, and the 19th 51 F. Cooler but still mild weather made up the rest of the month, most afternoons reaching the 30’s. Dry and warm weather persisted through much of March (mean temperature: 33 F), just four days recording snow and all but two of the 2PM readings at least in the 30’s. Mid-afternoon temperatures generally reached the 30’s and 40’s through the second week, but strong warming behind southerly winds brought 61 F on the 19th, the mercury staying in the 50’s all of the coming night. The Mississippi and the St. Peter’s both started their breakups the following day, the last ice disappearing from each on the 25th. Similar to a year ago, the closing week was very mild, with afternoons mostly in the 50’s and 60’s with thawing nights; the 28th hit 64 F at 2PM. Indicative of the region’s prolonged lack of precipitation, the Mississippi opposite the Post was noted “very low” on the 31st by Surgeon Robert E. Wood.
Welcome Spring Rains, But Late May Frosts – Spring ’30 was generally mild in temperature with some welcome rains in late April and early May. Killing and unseasonably late frosts, however, were also experienced. April (mean temperature: 51 F) brought more record heat over the first week, the mercury soaring to 81 F on the 5th, highest yet so early in the season by more than a week. Such prematurely high readings could only occur following droughty winters such as the one just passed, solar energy incident at the surface more available to heat the lower air and not, as during more normal early April periods, expended in snow-melting and/or evaporation of runoff. Much colder weather came on the 9th, however, the mercury just 40 F at 2PM with “snow and rain”, but more balmy afternoons came during the third week, several in the low to mid-70’s. Conditions over the remaining days were much cloudier with frequent rains, ten of the last twelve “cloudy” and seven having “rain”. Also over the interval, a “severe frost” was experienced on the 26th, the wording at least suggesting that early vegetation might have been damaged. May (mean temperature: 58 F) featured a freak heavy snow early in the month with a near-record late frost episode late. Following additional rains on the 1st and 3rd, an unseasonably late snowstorm dumped three inches on the 4th, temperatures 32 F at each of the three observation times. Readings quickly recovered to the 60’s by the end of the week, and to 80 F by the 9th. The balance of the month was mostly bright and sunny, with just five “cloudy” and three rainy days, respectively. On the 20th and 21st, however, two late frosts set in, the latter just two days shy of tying 1822’s late date mark. As is frequently the case after frost episodes this far into the season, a pronounced warming next ensued. Afternoon temperatures on the 27th and 28th reached 78 F and 80 F, respectively, 7AM readings on each day noted in the low 70’s.
Sweltering July, Almost Rainless August – Summer ’30 was warm and dry, especially July – the hottest calendar month locally for another 106 years. Total measurable rain-day count for June-August (12) was even less than last year’s total (16), about one-third of “normal”. June (mean temperature: 67 F) gave no indication of what was to come next month, the first three weeks pleasant to cool. Most afternoons were in the low to mid-70’s with predominant westerly winds, seven rains falling. The last ten were precipitation-free, 85 F read on the 30th for month’s the warmest temperature. July was a supreme example of the kind of sustained summer heat possible in this far corner of the Northwest. Monthly mean temperature (80 F) surpassed the previous calendar month high mark by 5 degrees F, not to be surpassed itself until infamous July 1936 (mean temperature that month: 81 F). Prevailing winds were observed from the south quarter on 28 days and just four rains fell. Down the Mississippi at Fort Crawford, Surgeon William Beaumont remarked in his register as to the “… almost perpetual southerly wind” … and the “… intense hot sun during the day”. Highest observed afternoon temperature at Snelling over the month was a comparatively moderate 94 F, but 20 days were between 88 F to 94 F, none lower than 82 F. July 1936, in contrast, featured a two-week concentration of spectacularly high temperatures (eight in the 100’s) with relatively seasonable readings for most of the other days. August 1830 was also warmer than normal (mean temperature: 72 F) but not nearly to the extent as July. Rain was recorded on only one day, during the first week. Afternoon temperatures over the first half continued to reach the low-to-mid-80’s regularly, but thereafter the mid-to-upper 70’s were the rule. A 90 F, however, was recorded on the 21st for the month’s maximum. Despite July’s oppressive heat and the scarcity of rain in both it and August, no explicit mention appears in any early history texts or newspapers regarding an 1830 drought. Indeed, agricultural history was made this summer as Philander Prescott, one of the original arrivals at the Cantonment New Hope site in 1819, successfully “undertook farming (first plowing) near Lake Calhoun” [Williams, 1881]. Evidently, April-June’s relatively more frequent rains and cooler temperatures helped avoid a repeat of last year.
Record Mild October and November – After a relatively seasonable September by recent years’ thermal standards, October and November brought two successive months of far above average warmth. September (mean temperature: 59 F) started summery enough, the first five afternoons ranging from 76 F to 83 F, nights mostly in the mid-60’s, but there was definitely an autumnal feel to the air on the 10th with afternoon temperatures only in the low 50’s. A cold rain also fell during the day, one of six precipitation-days for the month. The season’s first frost followed on the 15th, a number of afternoons over the next week also confined to the 50’s and 60’s. Warmer weather returned during the last week, the 26th reaching 79 F. October (mean temperature: 54 F) was 4 F warmer than last year’s record mildest, with no reported frost or subfreezing temperatures. Rain was noted on only three days. The first week continued warm and clear, the 1st hitting 80 F, diurnal temperature ranges for the other days generally in the 50’s for the mornings to the mid-to-upper 70’s for the afternoons. Cooler and cloudier weather predominated the middle two weeks, afternoons principally in the 50’s and 60’s, mornings in the 40’s and 50’s, but clearer much warmer weather moved in for the final seven days, the 25th and 26th with incredible mid-summer-like heat: 62 F, 80 F, and 72 F recorded at 7AM, 2PM, and 9PM of the former; 66 F, 82 F, and 76 F noted at the same times for the latter. November (mean temperature: 42 F) was exceptionally mild but very cloudy, warmer than all the previous eleven Novembers by at least 7 F. Temperatures over the first week, while significantly lower than the extraordinary levels of late October, were still quite mild, the afternoon of the 1st 61 F and that of the 4th 65 F. Thereafter, conditions settled into a monotonous pattern of dreary overcast skies but only slightly cooler temperatures. Twenty-two of the remaining 25 days were “cloudy”, daily temperatures confined almost exclusively to the high 40’s to low 50’s for the afternoons, the mid-30’s to low 40’s for the mornings. A few nights did drop below freezing, the month’s lowest, however, an unseasonably mild 27 F.
Severe Cold and Heavy Snows in December – December (mean temperature: 15 F) brought a gradual descent to extreme arctic cold after mid-month, accompanied by almost daily snows beginning late of the first week. The 1st was as balmy as any day of the previous three weeks, temperatures of 45 F, 53 F, and 47 F recorded at the prescribed times, thunder even heard during the day. Afternoon readings then trended downward over the succeeding days, the 20’s and 30’s being the rule by the second week. Also, starting with the 5th, twelve days out of the next fifteen, inclusive, had snow. While no amounts were noted, assuming appreciable accumulations on at least some of the days, the deepest covering yet witnessed so early in a season by the military personnel was likely present by mid-month. On the 15th, the mercury dipped to -4 F, the Mississippi “closed with ice” the next day. An arctic outbreak brought -19 F on the 19th, and next morning, the 20th, -26 F was registered at 7AM, lowest temperature ever recorded so early in a season here. Start of a long, cold winter, the remaining days were continuously subfreezing with mostly subzero mornings.