ANNUAL CLIMATOLOGICAL SUMMARY
FT. SNELLING MN
Beginning 1 January 1836, Ft. Snelling temperature observations were taken daily at or about local sunrise (designated as the "AM" observation), 1400 hours local solar time (designated as the "PM" observation) and 2100 hours local solar time (designated as the "evening" observation). Also, beginning 1 January 1836, wind and sky cover observations were taken twice daily, probably at or about sunrise and at 1400 hours local solar time. Beginning 1 July 1836, fort observers began taking and recording quantitative precipitation observations, using a conical rain gauge designed by Simeon DeWitt, chancellor of the New York university system. Like records from previous years, the 1836 record also includes 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 1836 observations were taken within the Ft. Snelling enclosure (on the bluffs overlooking the confluence of the Mississippi and Minnesota rivers) .
Shifting of morning temperature observations from 0700 hours to local sunrise largely eliminated (or at least significantly reduced) the effects of early morning sun contamination which, in years prior to 1836, distorted much of the fort's warm season temperature record. Therefore, with the possible exception of readings taken at 1400 hours (which, like corresponding readings from some years prior to 1836, may sometimes have been taken from instruments exposed to direct afternoon sunlight), 1836 temperatures conform to normal diurnal patterns and, as such, require no "sun pollution" adjustments.
The foregoing 1836 temperature record includes both unadjusted (UNADJ) and adjusted (ADJ) mean temperatures. Unadjusted values are the simple averages of fixed time readings taken daily at sunrise, 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 1836 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 1836 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 the first six months of 1836, 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 precipitation frequency record (e.g. number of days with snow, etc.) for the period, January-June 1836 . Prevailing wind values are based on entries indicating the direction of the wind as recorded by station observers on the morning and afternoon of each day during 1836. Prevailing monthly winds indicate the direction most frequently observed/recorded during any given month. Sky cover distributions are based on observations taken twice daily during 1836 : fair days are those with "fair" conditions noted at both observations; cloudy days are those with "cloudy" conditions noted at both observations; and "mixed" days are those with fair conditions noted at one observation and cloudy conditions noted at one observation.
Cold January: readings of -26 F and -10 F at 0700 and 1400 hours, respectively, on 31 January. Warm early January: reading of 36 F at sunrise on 7 January. Rain on 4, 6, 7, 16 January. Three inch snowfall noted on 10, 15 January. Cold early February: -24 F at sunrise on 1 February. One inch snowfall on 14 February; four inches of snow and high winds on 17 February; three inch snowfall on 28 February. Reading of -18 F at sunrise on 27 February. Cold March: readings of -16 F, -10 F, -15 F, -12 F, -12 F, -10F and -16 F at sunrise on 1, 2, 5, 6, 7, 10, 11 March, respectively. Reading of -6 F at sunrise on 22 March. Two inches of snow on 2 March: four inches of snow on 12 March. Snow and sleet with high winds on 16 March. Cold April: readings of 32 F, 31 F and 34 F at 1400 on 8, 9, 20 April, respectively. Reading of 14 F at sunrise on 10 April. Six inches of snow, 12-13 April. Severe storm with rain, snow and high winds on 20 April. Warm, dry, sunny (twenty six "fair" days) May. Afternoon temperatures near 90 F at mid-month. Sunny (twenty "fair" days) June. Reading of 42 F at sunrise on 8 June. Warm, wet July. Rainfalls of two inches on 10, 25 July. Reading of 63 F at 1400 on 28 July. Cool, wet August. Rainfall of 0.90 inches in one half hour on 2 August. Afternoon readings in the 60's F on many days during month: 62 F recorded at 1400 on 19 August. Sunrise readings in the 40's F, 20-23 August. Cool, wet September. Light frost noted on 5 September. Nearly four inches of rain recorded, 15-18 September. Reading of 40 F at sunrise on 9 September. Cold, dry October: reading of 22 F at sunrise on 4 October. Readings of 44 F, 44 F and 46 F at 1400 on 3, 4, 5 October, respectively. Sunrise readings in the low 20's F, 17-20 October: 18 F at sunrise on 21 October. Afternoon readings in the low 30's F, 16-20 October. Snowfall of about one inch noted on 18 October. Warm, sunny and virtually snowless November. Warm early December: readings near 50 F on 7, 8 December. Little precipitation during the first half of the month. Light snowfall on 19-20 December followed by first cold wave of the winter season: -22 F at sunrise on 21 December. Heavier snowfall on 23-24 December followed by a reading of -28 F at sunrise on 25 December. Mild weather during the closing days of December.