Minnesota (Fort Snelling) weather for the year 1839

Warmest Year to Date

In a major thermal turnaround, 1839 brought the warmest year in twenty years’ Fort Snelling history. Annual mean temperature (48 F) was six degrees warmer than 1838, surpassing also by 1 F the previous record high figures of 1825 and 1830. Total precipitation was barely over 21 inches, the least until 1852. Prolonged mild and warm spells occurred during all the seasons of the year, the cold spring and autumn spells that had marked the past several years a virtual non-occurrence. April set a high mark for mean temperature that still stands today, and October was the warmest yet in the Post record-keeping experience. The ’38-’39 winter’s snowfall was relatively light, and April through August rainfall was about 75% of average.

A Great Temperature Reversal — Mild Winter, Early Spring – The exceptionally persistent below average temperature regime of October, November, and December 1838 in reality turned out to be the “cold” phase of a great seven-month thermal anomaly oscillation. Almost from the very first day of 1839, temperature patterns shifted to unseasonably mild, continuing in this mode with few interruptions all the way through April. Similar type fall-to-winter-to-spring “see-saws”, not quite as pronounced as ’38-’39, are scattered throughout the local climatic record up to the present. January (mean temperature: 20 F) tied 1833 for second warmest to date, virtually no snow falling until the last few days. Ten of the first eleven reached at least thawing, five breaking 40 F, and a rare 0.20 inch rain fell on the 8th. After mid-month, the thawing days became more intermittent, and a few short cold snaps brought –10 F daybreak temperatures. On the 27th-30th, a massive snowstorm buried the Post with eleven inches, a bitter reservoir of arctic air drawn down in its wake; “Evening” of the 31st was already down to -14 F. February (mean temperature: 25 F), otherwise very mild, featured tremendous temperature gyrations over the first week, reminiscent of 1822 about this time. Climax of the great post-storm arctic surge, the 1st and 2nd brought -26 F and -25 F “A.M” readings, respectively, but in an even greater thermal rebound, the 3rd soared to 42 F. Another arctic front, however, plunged the temperature back to -14 F by next morning. Minus 22 and minus 19 F temperatures were read on the 5th and 6th, but the mercury then surged back to 44 F on the 7th. A steady mild/dry pattern now took hold, and fourteen of the remaining 21 days of the month reached the 40’s or higher, three surpassing 50 F. Three light snows totaling around one inch depth in addition to a 0.30 inch rain made up the precipitation falls. March (mean temperature: 30 F) exhibited a couple of abbreviated cold snaps that depressed its monthly mean somewhat. Total precipitation was 0.71 inches, including 2-3 inches’ snow. A late arctic spell opened the first few days, -10 F recorded on the 2nd and -16 F on the 3rd, but just three days later, on the 6th, the mercury reached 58 F. Following a “thunder & lightning” storm which left .48 inches’ rain and hail on the 12th, a second cold snap ensued, the next four days all below freezing with sunrise temperatures in the -3 F to 5 F range. The remaining days featured a steady warming trend, the 21st reaching 50 F, the 26th 58 F, the 27th 68 F, and the 31st, 72 F. No precipitation, rain or snow, fell over the last nineteen days.

Warm Spring – April and May brought very warm to seasonable temperatures and frequent rains, the early 1839 growing season, allowing for some May frosts, probably one of the more forward of the last twenty years. April was the warmest such month ever recorded in Twin Cities’ climatic history, average temperature (58 F) about 12 F above the modern “normal”, no freezing temperatures or snow experienced. Rains fell on eleven days to a total 2.71 inches. The first week was like mid-May or later, daily temperatures reaching the mid 70’s on most afternoons, following morning readings typically in the upper 40’s to low 50’s. The 3rd reached 77 F, about 30 F above normal for the day. Somewhat cooler conditions ensued over the next ten days, afternoons generally in the 60’s, a few mornings in the mid-30’s, but the last twelve were unseasonably warm again (and wet), five afternoons reaching 76 F or higher, the 26th hitting 84 F to tie 1829’s reading for highest temperature recorded in April. Five rains over the 22nd-27th also dropped 2.15 inches, including 1.35 inches on the 27th. May (mean temperature: 58 F) a seasonable month in temperature, was no warmer than April, average-wise. Total rainfall was 3.28 inches, almost all of it over the first two weeks. Cool weather set in immediately over the first few days, the mercury 32 F on the 3rd, light frost seen. Warmer temperatures accompanied by generous rains followed, the 6th reaching 85 F, 2.92 inches’ precipitation falling on this and the next six days through the 12th. Frost was again reported on the 14th accompanied by a sunrise temperature of 30 F, and the 15th and 16th were each 34 F at daybreak, but this was succeeded by a nearly week-long stretch of summer-like heat, afternoon 80’s recorded on five of six days over the 18th-23rd, three reaching 86 F.

Warm, Dry Summer – Summer ’39 was warm and relatively dry, long hot terms being felt in both July and August, the latter having a twenty-day rainless spell. June (mean temperature: 69 F) was only slightly warmer than average with light precipitation. Total fall was 1.80 inches on nine days, just 0.77 inch of this over the first three weeks. An early warm spell brought mid-to-upper 80’s temperatures on six straight days over the 6th-11th, but cool to pleasant weather prevailed thereafter all the way through the 28th, most afternoons in the 70’s to low 80’s, eight mornings in the 48 F to 52 F range. The closing two days were the month’s warmest, 90 F read on the 29th and 96 F on the 30th; the latter was the hottest June temperature registered in sixteen years. July (mean temperature: 76 F) tied its’ 1834 namesake for fourth hottest calendar month so far in Post history. Twelve days had “P. M.” readings in the 90’s, rain falling on seven to 3.50 inches, most of this (2.80 inches) coming over the 17th-20th. Hot weather was scattered throughout, a ten-day spell over the 19th-28th, however, being particularly oppressive, seven afternoons passing 90 F and five in succession over the 24th-28th reaching between 93 F and 95 F. August was relatively warm (mean temperature: 72 F) but dry, total rainfall just 1.04 inches on five falls. The first week continued warm, most afternoons in the upper 80’s, nights, though, in the relatively comfortable mid-50’s to low 60’s. Light showers dropped 0.09 inches on the 1st, but no additional falls came, however, until the 22nd. Hot weather set in again around mid-month with 96 F recorded on the 15th. Over the three-day stretch the 19th-21st; 95 F, 97 F, and 97 F temperatures were also registered. Cooler and wetter weather closed the last ten days, afternoons in the 70’s, nights in the 50’s; four rains left about an inch. During August some significant history was realized as the first sawmill in the St. Croix Valley began operations at Marine on St. Croix [Lass, 1976]. As would be recollected years later, water levels this season were particularly low [St. Paul Pioneer, 1865].

Dry Fall/Early Winter, Very Warm October – Infrequent precipitation falls and a record warm October marked the transition to winter. September was the year’s most anomalously cool month, mean temperature (57 F) about 2 F lower than the September average for the previous 19 years (1820-1838). Seven light to moderate rains produced 1.61 inches total. The 2nd and 3rd were summery, afternoon readings in the low 80’s, but autumnal weather quickly set to predominate the next two weeks. No afternoons warmer than the low 70’s were recorded over the interval and nighttime temperatures frequently dropped into the 40’s. The season’s first frost (“light”) arrived on the 10th, and a full-fledged visitation came on the 12th (mercury 35 F at sunrise). Afternoon readings were back in the mid-70’s to low 80’s on four successive days over the 18th to 21st with a couple of nights staying in the 60’s, but cooler, occasionally frosty weather ensued for the remaining days, a number of afternoons confined to the 50’s. Frost again visited on the 27th, the 29th recording 28 F. October (mean temperature: 55 F) surpassed 1830 as the warmest to date, 2.11 inches’ precipitation falling on seven days. Most of the latter came from a two-day storm over the second week. The first eight days brought a major warming, each of the afternoons reaching the 70’s to low 80’s, the nights exceptionally mild as indicated by the 62 F to 67 F sunrise temperatures noted for the 5th through 8th. A 1.65-inch rainstorm over the 10th-11th ushered in cooler temperatures, afternoons over the next week principally in the 60’s, nights still in the upper 40’s. A second, cooler outbreak brought the month’s first freezing temperatures on the 19th and 20th. Generally mild weather then returned for the remaining days, afternoons in the 50’s and 60’s, a few nights holding in 50’s. November (mean temperature: 30 F), relatively seasonable in temperature overall, had 1.66 inches’ precipitation, almost all of it from a two-day spell over the first week. Mild and overcast weather predominated the first six days, three afternoons in the low-to-mid-50’s, 1.60 inches of rain received over the 4th-5th. A steady, slightly cooler pattern with mostly “fair” skies prevailed over the next twelve, afternoons varying from the high 30’s to the mid-40’s, with nights in the 20’s. But an early arctic push brought 0 F to -3 F readings over the 24th-26th, the Mississippi freezing over on the 24th. The 29th, however, rebounded to 50 F again at the “P. M.” observation. The year and decade closed out with a mild and grey December, mean temperature (21 F) the warmest in six years, 20 1/2 “cloudy” days (counting half-days) the tally from the register. Eight snows left about eleven inches. Week one was overcast and thawing with mostly southerly winds and temperatures in the mid-30’s to mid-40’s night and day. Four inches’ snow was recorded, undoubtedly melting, though, soon after it landed. Sunnier and moderately colder weather prevailed over the next two, most afternoons in the 20’s, minus 3 felt on the 13th. The 21st through 26th, however, each had afternoons in the 30’s again, another four inches’ snow received. The year closed cold, daily temperatures over the 29th-31st in the -10 F to +10 F range.