ANNUAL CLIMATOLOGICAL SUMMARY
FT. SNELLING MN
The 1835 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 1835 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 1835. Specifically, 1835 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 1835's warm season average temperatures were elevated by direct exposure to early morning sunlight: the original record indicates, for example, that temperatures averaged about 67 F in August (as adjusted by Fisk, cited below), a value which, IF further adjusted for the probable effects of sun contamination , would be reduced to about 66 F.
The foregoing 1835 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 1835 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 1835 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 1835, 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 1835 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.
Warm, dry and cloudy (twenty three "cloudy" days) January. Brief cold early January. Afternoon readings in the 40's F on many days during the month. Southerly winds prevailing on sixteen days during January. Cold, dry and sunny (nineteen "fair" days) February. Reading of -30 F at 0700 on 7 February. Readings of -16 F and -13 F at 1400 on 6, 7 February, respectively. High winds on 6 February. Brief mid-month warm-up: reading of 49 F at 1400 on 12 February. Very cold late February: readings of -17 F and -18 F at 0700 on 26, 28 February, respectively. Cold early March. Warm late March : reading of 47 F at 0700 on 25 March. Twenty "fair" days during March. Cool, windy and cloudy (sixteen cloudy days) April. Hail on 3, 18, 27 April. One inch snowfall on 14 April. Probable minima of 20 F or lower each day, 13-16 April. Readings of 31 F at 1400 on 12, 13, 16 April. Warm, wet, sunny (nineteen "fair" days) May. Rain "throughout the day" on 7 May: reading of 46 F at 1400 on that date. Cool, rainy June. Readings in the low to mid-60's F at 1400 hours on 19, 20, 25, 27, 28, 29 June. Rain with high winds noted on 9, 12 June. Cool, sunny (twenty two "fair" days) July. Hazy atmosphere noted on several days during mid-July. Readings in the low to mid-60's F at 1400 hours, 6-8 July. Rain with high winds during the night of 29-30 July. Cool, wet but sunny (twenty four "fair" days) August. Readings of 59 F, 62 F, 60 F and 61 F at 1400 on 20, 25, 27, 28 August, respectively. Reading of 81 F at 0700 on 11 August . Cold September; frost on 20 September followed by heavy frost on 23 September. Readings of 50 F, 48 F and 50 F at 1400 on 20, 21, 22 September, respectively. Warm mid-October followed by very cold weather, 21-24 October. Readings of 28 F, 25 F, 28 F at 1400 on 21, 22, 23 October, respectively. Readings of 17 F and 19 F at 0700 on 23, 24 October, respectively. First prairie fires of autumn noted on 10 October. Smoky conditions noted on 12 October. Six inches of snow noted on 22 October. Very cold, sunny (twenty one "fair" days) November. Readings of 18 F and 16 F at 1400 on 18, 19 November, respectively. No 1400 readings above 32 F, 18-30 November. Readings of 5 F, 2 F, 5 F at 1400 on 21, 28, 30 November, respectively. Readings of -5 F, -10 F and -11 F at 0700 on 21, 22, 29 November, respectively. Prairie fires noted on 1 November. Spectacular auroral display combined with light from burning prairies noted on 17 November. Six inch snowfall noted on 10-11 November: three inch snowfall on 20 November. Dry, sunny (twenty four "fair" days) December. No snow recorded during December. Warm conditions at mid-month and again at the end of the month.