This report describes the historical weather record at the Charleston International Airport (Charleston Air Force Base) (Charleston, South Carolina, United States) during 1973. This station has records back to December 1947.
Charleston, South Carolina has a warm humid temperate climate with hot summers and no dry season. The area within 25 mi of this station is covered by forests (63%), oceans and seas (16%), croplands (12%), lakes and rivers (4%), and built-up areas (3%)
Daylight saving time (DST) was observed at Charleston, South Carolina during 1973. There were two time changes during 1973:
1973 was not a leap year, so it has 365 days and no February 29th. The first leap year before 1973 was 1972 and the first after was 1976.
The summer and winter solstices and the spring and fall equinoxes mark the passing of the seasons. They fall on nearly the same day each year, with differences of a day or two depending on the year. In 1973 they occurred on:
|Spring Equinox||Tuesday, 20 March 1973.|
|Summer Solstice||Thursday, 21 June 1973.|
|Fall Equinox||Sunday, 23 September 1973.|
|Winter Solstice||Saturday, 22 December 1973.|
The hottest day of 1973 was July 29, with a high temperature of 97°F. For reference, on that day the average high temperature is 90°F and the high temperature exceeds 95°F only one day in ten. The hottest month of 1973 was July with an average daily high temperature of 90°F.
Relative to the average, the hottest day was March 12. The high temperature that day was 88°F, compared to the average of 68°F, a difference of 20°F. In relative terms the warmest month was November, with an average high temperature of 73°F, compared to an typical value of 69°F.
The longest warm spell was from September 20 to October 17, constituting 28 consecutive days with warmer than average high temperatures. The month of September had the largest fraction of warmer than average days with 93% days with higher than average high temperatures.
The coldest day of 1973 was February 12, with a low temperature of 12°F. For reference, on that day the average low temperature is 41°F and the low temperature drops below 29°F only one day in ten. The coldest month of 1973 was February with an average daily low temperature of 35°F.
Relative to the average, the coldest day was February 12. The low temperature that day was 12°F, compared to the average of 41°F, a difference of 29°F. In relative terms the coldest month was February, with an average low temperature of 35°F, compared to an typical value of 42°F.
The longest cold spell was from August 19 to August 31, constituting 13 consecutive days with cooler than average low temperatures. The month of February had the largest fraction of cooler than average days with 68% days with lower than average low temperatures.
The clearest month of 1973 was November, with 70% of days being more clear than cloudy. The longest spell of clear weather was from April 10 to April 16, constituting 7 consecutive days that were clearer than they were cloudy.
The cloudiest month of 1973 was March, with 61% of days being more cloudy than clear. The longest spell of cloudy weather was from March 1 to March 12, constituting 12 consecutive days that were cloudier than they were clear.
This station reports both the quantity of liquid precipitation and categorical observations of precipitation (e.g., moderate rain, or heavy snow). Both are subject to erroneous reports, but the former is particularly prone to false reports, especially ones indicating an excessive quantity of precipitation. Please bear this in mind when reading the extrema reported in this section.
The day with the largest quantity of precipitation was June 11. That day saw 9.469" of liquid (or liquid equivalent) precipitation, compared to a median value of 0.201". The month with the most precipitation was June, with 26.252", compared to a median value of 4.429".
As determined by quantitative measurements, the longest dry spell was from October 5 to October 22, constituting 18 consecutive days with no measured precipitation. The month with the largest fraction of dry days was October, with 90% of days reporting no measured precipitation at all.
The month with the largest fraction of days with at least some measured precipitation was June, with 60% of days reporting some measured precipitation.
This station reports when significant weather events (including precipitation) are visually observed at or near the station. Such events do not always correspond to measured quantities of liquid equivalent precipitation, such as when the event is near by not at the station, or in the case of solid precipitation that does not melt in the collection basin.
The day in 1973 with the most precipitation observations was February 10. There were 24 hourly weather reports that day (out of a maximum of 24) in which some form of precipitation was observated at or near the station. The month with the most precipitation observations was June, with 119 hourly present weather reports involving some form of precipitation.
As determined by the present weather reports, the longest dry spell was from October 3 to October 22, constituting 20 consecutive days with no observed precipitation. The month with the largest fraction of days without observed precipitation was October, with 84% of days reporting no observed precipitation at all.
The month with the largest fraction of days with at least some observed precipitation was June, with 67% of days reporting some observed precipitation.
In this section we consider only those weather reports that indicate liquid precipitation. For the purposes of this analysis, we include thunderstorms even though some thunderstorms are not accompanied by liquid precipitation.
The month of 1973 with the largest number of those reports was June, with a total of 119 reports. The day with the largest number of those reports was June 11, with a total of 21 reports.
This station reports when snow is observed falling but does not report the quantity of snow that has fallen or the depth of snow on the ground.
In this section we consider hourly weather reports that contain an observation of falling snow. These reports do not necessarily correspond to accumulation.
The first reported snow fall in 1973 was on December 17; the last was on February 10. The month of 1973 with the largest number of those reports was February, with a total of 28 reports. The day with the largest number of those reports was February 10, with a total of 24 reports.
Humidity is an important factor in determining how weather conditions feel to a person experiencing them. Hot and humid days feel even hotter than hot and dry days because the high level of water content in humid air discourages the evaporation of sweat from a person's skin.
When reading the graph below, keep in mind that the hottest part of the day tends to be the least humid, so the daily low (brown) traces are more relevant for understanding daytime comfort than the daily high (blue) traces, which typically occur during the night. Applying that observation, the least humid month of 1973 was November with an average daily low humidity of 43%, and the most humid month was June with an average daily low humidity of 60%.
But it is important to keep in mind that humidity does not tell the whole picture and the dew point is often a better measure of how comfortable a person will find a given set of weather conditions. Please see the next section for continued discussion of this point.
Dew point is the temperature below which water vapor will condense into liquid water. It is therefore also related to the rate of evaporation of liquid water. Since the evaporation of sweat is an important cooling mechanism for the human body, the dew point is an important measurement for understanding how dry, comfortable, or humid a given set of weather conditions will feel.
Generally speaking, dew points below 50°F will feel a bit dry to some people, but comfortable to people accustomed to dry conditions; dew points from 50°F to 68°F are fairly comfortable to most people, and dew points above 68°F are increasingly uncomfortable, becoming oppressive around 77°F.
To take some examples, and basing our categorization on the daily high dew point in 1973, January had 18 dry days, 13 comfortable days, and no humid days; April had 9 dry days, 20 comfortable days, and 1 humid day; July had no dry days, no comfortable days, and 31 humid days; and October had 1 dry day, 23 comfortable days, and 7 humid days.
The highest sustained wind speed was 32 mph, occurring on March 17; the highest daily mean wind speed was 24 mph (March 17); and the highest wind gust speed was 45 mph (March 17).
The windiest month was April, with an average wind speed of 11 mph. The least windy month was July, with an average wind speed of 7 mph.
Visibility is the maximum distance at which a given reference object or light can be clearly discerned. In the United States, visibilities that are greater than or equal to 10 miles are typically reported as 10 miles.
The day of 1973 with the lowest average visibility was February 10, with an average visibility of 2.2 mi. The month with the lowest average visibility was March, with an average visibility of 6.5 mi. With an average visibility of 8.4 mi, the month of October had the highest average visibility.
The cloud ceiling is the altitude of the lowest layer of clouds that are at categorized as broken (mostly cloudy) or overcast (cloudy). If no such cloud layer exists then the ceiling is unlimited and no value is reported.
The day of 1973 with the lowest average cloud ceiling was August 29, with an average cloud ceiling of 49'. The month with the lowest average cloud ceiling was December, with an average cloud ceiling of 8326'. The month of July has the highest average cloud ceiling, with an average cloud ceiling of 15840'.