This report describes the historical weather record at the Tucson International Airport (Tucson, Arizona, United States) during 1979. This station has records back to October 1948.
Tucson, Arizona has a hot semi-arid steppe climate. The area within 25 mi of this station is covered by shrublands (70%), grasslands (23%), forests (4%), and built-up areas (3%)
Daylight saving time (DST) was not observed at Tucson, Arizona during 1979.
1979 was not a leap year, so it has 365 days and no February 29th. The first leap year before 1979 was 1976 and the first after was 1980.
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 1979 they occurred on:
|Spring Equinox||Wednesday, 21 March 1979.|
|Summer Solstice||Thursday, 21 June 1979.|
|Fall Equinox||Sunday, 23 September 1979.|
|Winter Solstice||Saturday, 22 December 1979.|
The hottest day of 1979 was July 9, with a high temperature of 109°F. For reference, on that day the average high temperature is 100°F and the high temperature exceeds 107°F only one day in ten. The hottest month of 1979 was July with an average daily high temperature of 100°F.
Relative to the average, the hottest day was December 18. The high temperature that day was 78°F, compared to the average of 64°F, a difference of 14°F. In relative terms the warmest month was December, with an average high temperature of 68°F, compared to an typical value of 65°F.
The longest warm spell was from September 20 to October 21, constituting 32 consecutive days with warmer than average high temperatures. The month of October had the largest fraction of warmer than average days with 84% days with higher than average high temperatures.
The coldest day of 1979 was November 22, with a low temperature of 24°F. For reference, on that day the average low temperature is 44°F and the low temperature drops below 36°F only one day in ten. The coldest month of 1979 was January with an average daily low temperature of 40°F.
Relative to the average, the coldest day was November 22. The low temperature that day was 24°F, compared to the average of 44°F, a difference of 20°F. In relative terms the coldest month was November, with an average low temperature of 44°F, compared to an typical value of 47°F.
The longest cold spell was from August 11 to August 28, constituting 18 consecutive days with cooler than average low temperatures. The month of March had the largest fraction of cooler than average days with 71% days with lower than average low temperatures.
The clearest month of 1979 was April, with 77% of days being more clear than cloudy. The longest spell of clear weather was from August 19 to September 1, constituting 14 consecutive days that were clearer than they were cloudy.
The cloudiest month of 1979 was January, with 52% of days being more cloudy than clear. The longest spell of cloudy weather was from September 30 to October 6, constituting 7 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 July 20. That day saw 1.110" of liquid (or liquid equivalent) precipitation, compared to a median value of 0.083". The month with the most precipitation was January, with 2.685", compared to a median value of 0.819".
As determined by quantitative measurements, the longest dry spell was from September 7 to October 21, constituting 45 consecutive days with no measured precipitation. The month with the largest fraction of dry days was October, with 97% of days reporting no measured precipitation at all.
The month with the largest fraction of days with at least some measured precipitation was January, with 32% 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 1979 with the most precipitation observations was January 17. There were 16 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 January, with 72 hourly present weather reports involving some form of precipitation.
As determined by the present weather reports, the longest dry spell was from November 9 to December 12, constituting 34 consecutive days with no observed precipitation. The month with the largest fraction of days without observed precipitation was November, with 97% of days reporting no observed precipitation at all.
The month with the largest fraction of days with at least some observed precipitation was August, with 52% of days reporting some observed precipitation.
Either snow is exceptionally rare at this location or this station did not reliably report it during 1979.
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 1979 was April with an average daily low humidity of 11%, and the most humid month was January with an average daily low humidity of 35%.
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 1979, January had 30 dry days, 1 comfortable day, and no humid days; April had 30 dry days, no comfortable days, and no humid days; July had 11 dry days, 18 comfortable days, and 2 humid days; and October had 29 dry days, 2 comfortable days, and no humid days.
The highest sustained wind speed was 62 mph, occurring on September 10; the highest daily mean wind speed was 17 mph (September 15); and the highest wind gust speed was 46 mph (August 16).
The windiest month was June, with an average wind speed of 9 mph. The least windy month was January, 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 1979 with the lowest average visibility was January 10, with an average visibility of 19.3 mi. The month with the lowest average visibility was January, with an average visibility of 34.6 mi. With an average visibility of 43.4 mi, the month of June 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 1979 with the lowest average cloud ceiling was January 29, with an average cloud ceiling of 1947'. The month with the lowest average cloud ceiling was September, with an average cloud ceiling of 11919'. The month of October has the highest average cloud ceiling, with an average cloud ceiling of 24540'.