(Source: Michigan State Climatologist's Office)

Introduction

Traverse City, located in north central Grand Traverse County of the Northwest Lower Climatic Division, is at the south end of the west arm of Grand Traverse Bay. The Old Mission Peninsula extends northward between the west arm and the east arm of Grand Traverse Bay about 15 miles, with the Bay itself opening into Lake Michigan about 30 miles north of Traverse City. The surrounding terrain is hilly and soils are predominantly sandy loam. For additional county soil information, please contact the Michigan Department of Agriculture (MDA)/Environmental Division/Soil Conservation Program, the USDA/Soil Conservation Service, the local Soil Conservation District, or the county Cooperative Extension Service (CES). For detailed county agricultural statistics please refer to the publication: "1988 County Food and Agricultural Development Statistics" produced by the MDA in cooperation with the USDA/Michigan Agricultural Statistics Service (MASS), or contact the MDA/Press and Public Affairs Division, the MASS, or the county CES.

Lake Effect

The lake effect on Traverse City's climate is quite strong during much of the year. The lake effect increases cloudiness and snowfall during the fall and winter and also modifies temperatures, keeping them cooler during the late spring and early summer, and warmer during the late fall and early winter. In the late winter as ice builds up on Grand Traverse Bay and Lake Michigan, Traverse City is subjected to temperature variations which are more closely associated with interior locations. Cherry orchards are found on the Old Mission Peninsula and on many of the hillsides along the east shore of the east arm of Grand Traverse Bay where prevailing westerly winds and the cold lake water is most effective in modifying the climate. Diminished wind speeds or winds which do not traverse large unfrozen lakes often produce clearing skies and the colder temperatures expected at continental locations.

General Climate

Because the day-to-day weather is controlled by the movement of pressure systems across the nation, this area seldom experiences prolonged periods of hot, humid weather in the summer or extreme cold during the winter. Long-term wind and humidity records are not available for this location, but these data should be similar to the following values which were observed at the National Weather Service Office in Houghton Lake. The prevailing wind is westerly, averaging 9 mph. The strongest one-minute wind speed, 40 mph, was recorded in June 1969 and January 1972. The average 1 P.M. relative humidity varies from 51% for May to 78% for December, and averages 63% annually.

Long-term Temperature Averages and Extremes

Summers are dominated by moderately warm temperatures with a 1951-80 average of 9 days exceeding the 90 F mark. During the same period 5 days in 3 different years were 100 F or higher. The lake influence was reflected in the minimum temperatures; an average of 164 days was 32 F or lower, an average of 13 days was 0 F or lower, and no year stayed above 0 F. The highest average monthly maximum temperature of 87.3 F was recorded July 1955, and the lowest average monthly minimum temperature of -1.5 F was recorded February 1979. The following temperature extremes, based on the time period of this station's published record, are: maximum, 105 F, recorded July 7, 1936; minimum, -37 F, recorded February 17, 1979; warmest monthly mean, 75.3 F, recorded July 1955; and coldest monthly mean, 9.2 F, recorded February 1979.

Degree-days

Heating and cooling degree-day data are used as an index of the heating and cooling requirements for buildings which are proportional to the number of degree-days. Heating degree-days for a single day are obtained by subtracting the mean temperature from 65 F when the mean temperature is below 65 F. Cooling degree-days for a single day are obtained by subtracting 65 F from the mean temperature when the mean temperature is above 65 F. Each are then summed to yield monthly totals. The average heating degree-days for January was 1396 while October was 490. The average cooling degree-days for July was 157 while May was 20.

Freezing Temperatures

Based on the 1951-80 period, the average date of the last freezing temperature in the spring was May 24, while the average date of the first freezing temperature in the fall was October 3. The freeze-free period, or growing season, averaged 132 days annually.

Rainfall and Snow

Precipitation was well distributed throughout the year with the crop season, April-September, receiving an average of 17.55 inches or 59% of the average annual total for the 1951-80 period. During this same period the average wettest month was September with 3.60 inches, while the average driest month was February with 1.41 inches. The following precipitation extremes, based on the time period of this station's published record, are: greatest published 24-hour total, 4.30 inches, recorded August 22-23, 1898; greatest monthly total, 10.78 inches, recorded May 1942; and least monthly total, 0.00 inches, recorded March 1889.

Summer precipitation comes mainly in the form of afternoon showers and thundershowers. Annually, thunderstorms will occur on an average of 31 days. Michigan is located on the northeast fringe of the Midwest tornado belt. The lower frequency of tornadoes occurring in Michigan may be, in part, the result of the colder water of Lake Michigan during the spring and early summer months, a prime period of tornado activity. During 1950-87, Michigan has averaged 15 tornadoes each year. During this same period, 4 tornadoes occurred within the county.

The 1950-51 through 1979-80 average seasonal snowfall was 87.0 inches. During this period, 112 days per season averaged 1 inch or more of snow on the ground, but varied greatly from season to season. The following snowfall extremes, based on the time period of this station's published record, are: greatest observation-day total, 14.4 inches, recorded December 16, 1972; greatest monthly total, 57.9 inches, recorded January 1982; greatest seasonal total, 136.9 inches, recorded during 1984-85; least seasonal total, 30.8 inches, recorded during 1936-37; and greatest snow depth, 50 inches, recorded February 26, 1904.

Evaporation and Soil Moisture

Evaporation data from the Class "A" pan were not available for this station, but these data should be similar to those observed at Lake City. During 1960-80, the pan evaporation for May through October exceeded the average precipitation by 55%. Therefore, soil moisture replenishment during the fall and winter months plays an important role in the success of agriculture for this area. While drought occurs periodically, the Palmer Drought Index indicated drought conditions reached extreme severity only 2% of the time.

Station History of Traverse City

Observations began on November 20, 1872 and continued through January 1877. The station was re-established in January 1882. The earliest published records for this station are for January 1882. On June 1, 1896 the station was located at the GR & I Railroad Station. The exact locations of the above stations are unknown. On July 7, 1927 the station was moved to the Water Works Plant, 0.5 mi. NW of the post office (PO). On April 8, 1941 the station was moved to the Municipal Airport, 2.5 mi. SE of the PO. The station has been at this location to the present.

For more information please contact:

Michigan Departent of Agriculture, Climatology Program
417 Natural Science Building
Michigan State University
East Lansing, MI 48824

Voice (517)373-8338 (517)355-0231
BBS (517)336-1075
FAX (517)336-1076