ANNUAL CLIMATOLOGICAL SUMMARY
FT. SNELLING MN
The 1834 Ft. Snelling climatological record consists of fixed time temperature readings taken daily at or about 0700, 1400 and 2100 hours local solar time; single daily entries indicating the prevailing direction of the wind and the general condition of the sky; intermittent records of snowfall and/or snow cover; episodic records of phenological, hydrological, astronomical and/or other natural events (windstorms, prairie fires, etc.); descriptive entries indicating the general duration (and, in some instances, the intensity) of precipitation; precipitation type ; and special atmospheric phenomena (fog, smoke, etc.). So far as can be determined, all 1834 observations were taken within the Ft. Snelling enclosure (on the bluffs overlooking the confluence of the Mississippi and Minnesota rivers) .
Analysis of the relationship between 0700, 1400 and 2100 readings indicates that the station thermometer was probably exposed to direct morning and/or afternoon sunlight during at least some portion of the late spring and summer months of 1834. Specifically, 1834 summer temperature records (May through August) include numerous 0700 readings exceeding or equalling 2100 readings (thereby reversing or nearly reversing normal summertime diurnal patterns). Such patterns obviously suggest that 1834's warm season average temperatures were elevated by direct exposure to early morning sunlight: the original record indicates, for example, that temperatures averaged about 76 F in July (as adjusted by Fisk, cited below), a value which, IF further adjusted for the probable effects of sun contamination , would be reduced to about 75 F.
The foregoing 1834 temperature record includes both unadjusted (UNADJ) and adjusted (ADJ) mean temperatures. Unadjusted values are the averages of fixed time readings taken daily at 0700, 1400 and 2100 hours . Adjusted averages are from Charles J. Fisk's 1984 "Reconstruction of Daily 1820-1872 Minneapolis-St. Paul Temperature Observations". These values were obtained by averaging statistically derived estimates of the daily maxima and minima that would have been recorded had the Ft. Snelling station been equipped with self-registering thermometers read and re-set at midnight . The foregoing 1834 record also includes both the monthly and annual extreme temperatures (highest daily minimum, lowest minimum, etc.) estimated by Fisk and the monthly extremes actually recorded/observed (OBSRV) by fort observers. All 1834 temperature distributions (e.g. days 90 F or higher, 32 F or lower, etc.) are based on Fisk's estimates of daily maxima and minima.
Although no quantitative precipitation records were kept at Ft. Snelling during 1834, extant records do, as noted, contain entries indicating precipitation type and, in some instances precipitation intensity (e.g. light snow, heavy rain, etc.). These records are the basis of the foregoing 1834 precipitation frequency record (e.g. number of days with snow, etc.) . Prevailing wind values, similarly, are based on entries indicating the predominate direction of the wind on each day of the month. Prevailing monthly winds indicate the direction most frequently observed/recorded during any given month.
Extremely cold January: readings of -27 F, -29 F, -32 F and -31 F at 0700 hours on 2, 3, 4, 5 January, respectively. Readings of -12 F and -11 F at 1400 hours on 3, 4 January, respectively. Probable minimum near -30 F on 20 January. Nineteen "fair" days during January. Post surgeon noted that "we have been shut up in the fort and confined to our rooms owning to excessive cold [during January]...". Brief thaw on 16 January accompanied by rain. Dry and near record warm February. Readings of 47 F, 50 F, 51 F and 50 F at 1400 hours on 3, 4, 5, 6 February, respectively. Readings of 33 F and 37 F at 0700 on 10, 20 February, respectively. Much fair weather with south to southwesterly winds during the first half of February. Dry March with warmth early in the month and colder conditions during the latter part of the month. Thunderstorm with hail on 6 March. Warm, sunny (twenty four "fair" days) April. Readings in the 70's F to 80 F at 1400 hours, 9-15 April. Warm, rainy May. Reading of 90 F at 1400 hours on 22 May. Readings of 78 F, 78 F and 80 F at 0700 on 21, 25 and 26 May, respectively . Reading of 48 F at 1400 hours on 28 May. Cool, rainy June. Heavy rain with "high winds" on 9 June. Reading of 60 F at 1400 on 27 June. Very warm and sunny (twenty nine "fair" days) July. Readings in the low 90's F each day, 20-25 July. Readings of 86 F at 0700 on 6, 24 July. Heavy thunderstorm accompanied by damaging hail during the early morning hours of 8 July: extensive damage to windows in the fort barracks. Warm but cloudy (fifteen cloudy days) August. Readings in the 80's F at 0700 hours each day, 5-9 August. Cool, rainy September. Smoke from prairie fires noted on 13 September. Heavy frost with ice formation to one-half inch during the night of 26 September. Overnight minima near 25 F probable on 27, 28 September. Readings of 46 F, 45 F and 46 F at 1400 on 26, 27, 28 September, respectively. Smoke from prairie fires noted on 10, 15 October. Reading of 25 F at 0700 on 13 October. Heavy rain on 1 October. High winds and snow squalls on 18 October. Very warm and sunny (nineteen "fair" days) November. Reading of 66 F at 0700 on 1 November. Reading of 64 F at 1400 on 20 November. Six inch snowfall on 30 November. Warm, relatively dry and sunny (eighteen "fair" days) December. Temperatures near 50 F on 13 December. Snow with high winds on 7 December. Warm late December: little or no snow cover likely at the end of the month.