This report describes the historical weather record at the Chicago Midway International Airport (Chicago, Illinois, United States) during 1948. This station has records back to January 1948.
Chicago, Illinois has a humid continental climate with hot summers and no dry season. The area within 25 mi of this station is covered by built-up areas (36%), oceans and seas (24%), grasslands (23%), croplands (14%), and forests (3%)
Daylight saving time (DST) was observed at Chicago, Illinois during 1948. There were two time changes during 1948:
1948 was a leap year and thus has 366 days rather than the normal 365. Leap years occur every fourth year and the extra day is always February 29th. In 1948 February 29th falls on a Sunday.
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 1948 they occurred on:
|Spring Equinox||Saturday, 20 March 1948.|
|Summer Solstice||Monday, 21 June 1948.|
|Fall Equinox||Thursday, 23 September 1948.|
|Winter Solstice||Tuesday, 21 December 1948.|
The hottest day of 1948 was August 24, with a high temperature of 98°F. For reference, on that day the average high temperature is 81°F and the high temperature exceeds 89°F only one day in ten. The hottest month of 1948 was July with an average daily high temperature of 85°F.
Relative to the average, the hottest day was April 25. The high temperature that day was 85°F, compared to the average of 63°F, a difference of 22°F. In relative terms the warmest month was April, with an average high temperature of 63°F, compared to an typical value of 59°F.
The longest warm spell was from October 25 to November 6, constituting 13 consecutive days with warmer than average high temperatures. The month of September had the largest fraction of warmer than average days with 60% days with higher than average high temperatures.
The coldest day of 1948 was January 17, with a low temperature of -10°F. For reference, on that day the average low temperature is 17°F and the low temperature drops below 0°F only one day in ten. The coldest month of 1948 was January with an average daily low temperature of 11°F.
Relative to the average, the coldest day was March 12. The low temperature that day was 1°F, compared to the average of 30°F, a difference of 29°F. In relative terms the coldest month was January, with an average low temperature of 11°F, compared to an typical value of 18°F.
The longest cold spell was from January 13 to February 4, constituting 23 consecutive days with cooler than average low temperatures. The month of May had the largest fraction of cooler than average days with 94% days with lower than average low temperatures.
The longest freezing spell was from January 21 to February 13, constituting 24 consecutive days with temperatures strictly below freezing.
The clearest month of 1948 was August, with 55% of days being more clear than cloudy. The longest spell of clear weather was from May 18 to May 30, constituting 13 consecutive days that were clearer than they were cloudy.
The cloudiest month of 1948 was March, with 68% of days being more cloudy than clear. The longest spell of cloudy weather was from October 30 to November 7, constituting 9 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 September 8. That day saw 1.370" of liquid (or liquid equivalent) precipitation, compared to a median value of 0.197". The month with the most precipitation was July, with 3.197", compared to a median value of 2.650".
As determined by quantitative measurements, the longest dry spell was from January 1 to July 10, constituting 192 consecutive days with no measured precipitation. The months January, February, March, April, May, and June were completely without measured precipitation.
The month with the largest fraction of days with at least some measured precipitation was November, with 37% 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 1948 with the most precipitation observations was January 1. There were 23 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 March, with 209 hourly present weather reports involving some form of precipitation.
As determined by the present weather reports, the longest dry spell was from May 16 to June 4, constituting 20 consecutive days with no observed precipitation. The month with the largest fraction of days without observed precipitation was October, with 74% of days reporting no observed precipitation at all.
The month with the largest fraction of days with at least some observed precipitation was January, with 61% 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 1948 with the largest number of those reports was May, with a total of 102 reports. The day with the largest number of those reports was May 6, 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 1948 was on November 13; the last was on April 13. The month of 1948 with the largest number of those reports was January, with a total of 130 reports. The day with the largest number of those reports was January 1, with a total of 18 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 1948 was August with an average daily low humidity of 43%, and the most humid month was November 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 1948, January had 31 dry days, no comfortable days, and no humid days; April had 20 dry days, 10 comfortable days, and no humid days; July had no dry days, 15 comfortable days, and 16 humid days; and October had 24 dry days, 7 comfortable days, and no humid days.
The highest sustained wind speed was 40 mph, occurring on April 8; the highest daily mean wind speed was 27 mph (February 28);
The windiest month was April, with an average wind speed of 12 mph. The least windy month was August, 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 1948 with the lowest average visibility was November 1, with an average visibility of 0.7 mi. The month with the lowest average visibility was February, with an average visibility of 5.7 mi. With an average visibility of 9.7 mi, the month of April 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 1948 with the lowest average cloud ceiling was March 20, with an average cloud ceiling of 0'. The month with the lowest average cloud ceiling was December, with an average cloud ceiling of 2316'. The month of August has the highest average cloud ceiling, with an average cloud ceiling of 5921'.