The Mississippi at St. Louis is frequently frozen over, and is crossed on the ice, and occasionally for several weeks. The hot season is longer, though not more intense, than occasionally for a day or two in New England.
During the years 1817-18-19, the Rev. Mr. Giddings, at St. Louis, made a series of observations upon Fahrenheit's thermometer.
| Deg. | Hund. | |
| Mean temperature for 1817 | 55 | 52 |
| Mean temperature from the beginning of May, 1818, to the end of April, 1819 | 56 | 98 |
| Mean temperature for 1820 | 56 | 18 |
The mean of these results is about fifty-six degrees and a quarter.
The mean temperature of each month during the above years, is as follows:
| Deg. | Hund. | |
| January | 30 | 62 |
| February | 38 | 65 |
| March | 43 | 13 |
| April | 58 | 47 |
| May | 62 | 66 |
| June | 74 | 47 |
| July | 78 | 66 |
| August | 72 | 88 |
| September | 70 | 10 |
| October | 59 | 00 |
| November | 53 | 13 |
| December | 34 | 33 |
The mean temperature of the different seasons is as follows:
Winter, 34.53—Spring, 54.74—Summer, 74.34—Autumn, 60.77.
The greatest extremes of heat and cold during my residence of eighteen years, in the vicinity of St. Louis, is as follows:
Greatest heat in July 1820, and July 1833, 100 degrees. Greatest cold January 3d, 1834, 18 degrees below zero,—February 8th, 1835, 22 degrees below zero.