This report describes the historical weather record at the Hartsfield-Jackson Atlanta International Airport (Atlanta, Georgia, United States) during 1970. This station has records back to December 1947.
Atlanta, Georgia has a warm humid temperate climate with hot summers and no dry season. The area within 25 mi of this station is covered by croplands (47%), forests (29%), and built-up areas (23%)
Daylight saving time (DST) was observed at Atlanta, Georgia during 1970. There were two time changes during 1970:
1970 was not a leap year, so it has 365 days and no February 29th. The first leap year before 1970 was 1968 and the first after was 1972.
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 1970 they occurred on:
|Spring Equinox||Saturday, 21 March 1970.|
|Summer Solstice||Sunday, 21 June 1970.|
|Fall Equinox||Wednesday, 23 September 1970.|
|Winter Solstice||Tuesday, 22 December 1970.|
The hottest day of 1970 was July 3, with a high temperature of 97°F. For reference, on that day the average high temperature is 88°F and the high temperature exceeds 94°F only one day in ten. The hottest month of 1970 was July with an average daily high temperature of 87°F.
Relative to the average, the hottest day was November 30. The high temperature that day was 76°F, compared to the average of 59°F, a difference of 17°F. In relative terms the warmest month was September, with an average high temperature of 86°F, compared to an typical value of 82°F.
The longest warm spell was from September 14 to September 28, constituting 15 consecutive days with warmer than average high temperatures. The month of September had the largest fraction of warmer than average days with 87% days with higher than average high temperatures.
The coldest day of 1970 was January 9, with a low temperature of 3°F. For reference, on that day the average low temperature is 35°F and the low temperature drops below 21°F only one day in ten. The coldest month of 1970 was January with an average daily low temperature of 28°F.
Relative to the average, the coldest day was January 9. The low temperature that day was 3°F, compared to the average of 35°F, a difference of 32°F. In relative terms the coldest month was January, with an average low temperature of 28°F, compared to an typical value of 34°F.
The longest cold spell was from July 4 to July 23, constituting 20 consecutive days with cooler than average low temperatures. The month of July had the largest fraction of cooler than average days with 81% days with lower than average low temperatures.
The clearest month of 1970 was September, with 50% of days being more clear than cloudy. The longest spell of clear weather was from November 3 to November 9, constituting 7 consecutive days that were clearer than they were cloudy.
The cloudiest month of 1970 was April, with 57% of days being more cloudy than clear. The longest spell of cloudy weather was from April 24 to May 4, constituting 11 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 March 19. That day saw 4.614" of liquid (or liquid equivalent) precipitation, compared to a median value of 0.261". The month with the most precipitation was March, with 6.980", compared to a median value of 4.630".
As determined by quantitative measurements, the longest dry spell was from November 21 to December 11, constituting 21 consecutive days with no measured precipitation. The month with the largest fraction of dry days was September, with 83% of days reporting no measured precipitation at all.
The month with the largest fraction of days with at least some measured precipitation was July, with 42% 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 1970 with the most precipitation observations was January 6. There were 21 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 October, with 101 hourly present weather reports involving some form of precipitation.
As determined by the present weather reports, the longest dry spell was from November 21 to December 11, constituting 21 consecutive days with no observed precipitation. The month with the largest fraction of days without observed precipitation was May, with 77% of days reporting no observed precipitation at all.
The month with the largest fraction of days with at least some observed precipitation was March, with 52% 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 1970 with the largest number of those reports was October, with a total of 101 reports. The day with the largest number of those reports was May 3, 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 1970 was on December 30; the last was on February 10. The month of 1970 with the largest number of those reports was January, with a total of 18 reports. The day with the largest number of those reports was January 6, with a total of 5 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 1970 was February with an average daily low humidity of 37%, and the most humid month was August with an average daily low humidity of 55%.
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 1970, January had 27 dry days, 4 comfortable days, and no humid days; April had 7 dry days, 20 comfortable days, and 3 humid days; July had no dry days, 5 comfortable days, and 26 humid days; and October had 4 dry days, 27 comfortable days, and no humid days.
The highest sustained wind speed was 35 mph, occurring on July 4; the highest daily mean wind speed was 17 mph (April 2);
The windiest month was January, with an average wind speed of 9 mph. The least windy month was September, with an average wind speed of 6 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 1970 with the lowest average visibility was December 20, with an average visibility of 0.9 mi. The month with the lowest average visibility was August, with an average visibility of 7.7 mi. With an average visibility of 12.0 mi, the month of February had the highest average visibility.
This station did not reliably report the cloud ceiling during 1970.