Average Weather On October 12 For Chicago, Illinois, USA

Location

This report describes the typical weather at the O'Hare International Airport (Chicago, Illinois, United States) weather station over the course of an average October 12. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.

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 (37%), grasslands (36%), oceans and seas (22%), forests (3%), and croplands (3%).

Temperature

The temperature typically varies from 47°F to 61°F and is rarely below 36°F or above 75°F.

Temperature

Average hourly temperature (black) with percentil bands (inner band from 25th to 75th percentile, outer band from 10th to 90th percentile).

The coolest hours of the day are from 2am to 9am with the coldest at 7am, at which time the temperature is below 53°F three days out of four.

The warmest hours of the day are from noon to 6pm with the hottest at 3pm, at which time the temperature is above 54°F three days out of four.

The day has gained half its heat by 10am and lost it again by 9pm.

Temperature Bands

The average fraction of time spent in various temperature bands: frigid (below 15°F), freezing (15°F to 32°F), cold (32°F to 50°F), cool (50°F to 65°F), comfortable (65°F to 75°F), warm (75°F to 85°F), hot (85°F to 100°F) and sweltering (above 100°F).

Sun

On October 12 the Sun rises at 7:01am and sets at 6:13pm.

Solar noon is at 12:37pm.

For reference, on the longest day of the year the Sun rises at 5:16am and sets at 8:30pm, while on the shortest day of the year it rises at 7:16am and sets at 4:23pm.

Astronomical twilight begins and ends 92 minutes before sunrise and after sunset at 5:28am and 7:46pm, respectively.

Nautical twilight begins and ends 60 minutes before sunrise and after sunset at 6:00am and 7:14pm, respectively.

Civil twilight begins and ends 28 minutes before sunrise and after sunset at 6:33am and 6:42pm, respectively.

Solar twilight begins and ends 37 minutes after sunrise and before sunset at 7:39am and 5:35pm, respectively.

Solar Elevation

Elevation of the Sun above (positive) or below (negative) the horizon (black line). Yellow and gray fills indicate day and night, respectively. Light gray lines are the corresponding curves for the winter and summer equinoxes.

Clouds

The median cloud cover ranges from 60% (partly cloudy) to 80% (mostly cloudy).

At 2am, the clearest time of the day, the sky is clear, mostly clear, or partly cloudy 56% of the time, and overcast or mostly cloudy 44% of the time.

At 2pm, the cloudiest time of the day, the sky is overcast, mostly cloudy, or partly cloudy 69% of the time, and clear or mostly clear 31% of the time.

The sky is typically clearing in earnest by 9pm.

The clouds have typically started forming in earnest by 8am.

Median Cloud Cover

Median hourly cloud coverage fraction (black line) with percentile bands (inner band from 40th to 60th percentile, outer band from 25th to 75th percentile).

Cloud Cover Types

The fraction of time spent in each of the five sky cover categories. From top (most blue) to bottom (most gray), the categories are clear, mostly clear, partly cloudy, mostly cloudy, and overcast. Pink indicates missing data. Outside the United States clear skies are often reported ambiguously, leading them to be lumped in with the missing data.

Precipitation

There is a 45% chance that precipitation will be observed at some point during the day.

The average measured liquid-equivalent quantity of precipitation is 0.094". Among only those days for which there is at least some measured precipitation, the average is 0.302" and the total rarely exceeds 0.648".

Probability of Precipitation

The fraction of days in which various types of precipitation are observed. If more than one type of precipitation is reported in a given day, the more severe precipitation is counted. For example, if light rain is observed in the same day as a thunderstorm, that day counts towards the thunderstorm totals. The order of severity is from the top down in this graph, with the most severe at the bottom.

When precipitation does occur it is most often in the form of slight rain (40% of days with precipitation have at worst slight rain), moderate rain (32%), thunderstorms (12%), and slight snow (7%).

Precipitation is most likely around 11pm and least likely around 1pm.

Types of Precipitation

Relative frequency of various types of precipitation over the course of a typical October 12.

Snow

Either snow is exceptionally unlikely to fall at this location on October 12 or this station does not reliably report precipitation types.

Humidity

The relative humidity typically ranges from 56% (mildly humid) to 81% (humid), rarely dropping below 36% (comfortable), or exceeding 95% (very humid).

The air is driest at 3pm, at which time the relative humidity is less than 67% (mildly humid) three days out of four; it is most humid at 5am, exceeding 74% (humid) three days out of four.

Relative Humidity

Average hourly humidity (black line) with percentile bands (inner bands from 25th to 75th percentile, outer bands from 10th to 90th percentile).

Dew Point

The dew point ranges from 41°F to 43°F with an average of 42°F.

For reference, comfortable indoor conditions should have a relative humidity between 30% and 50% with a dew point of less than 65°F.

Dew Point

Average hourly dew point (black line) with percentile bands (inner bands from 25th to 75th percentile, outer bands from 10th to 90th percentile).

Wind

Sustained wind speeds typically vary from 8 mph to 12 mph (gentle breeze to moderate breeze) over the course of the day.

The peak sustained wind speed typically occurs around 4pm and is rarely outside the range 6 mph to 18 mph (light breeze to fresh breeze).

The wind is most calm around 5am, rarely exceeding 14 mph (moderate breeze).

Wind Speed

Average hourly wind speed (black line) with percentile bands (inner bands from 25th to 75th percentile, outer bands from 10th to 90th percentile).

The wind is most often out of the south (21% of the time), west (17% of the time), south west (16% of the time), north west (11% of the time), and north (10% of the time).

Wind Directions

The fraction of time spent with the wind blowing from the various directions over the entire day. Values do not sum to 100% because the wind direction is undefined when the wind speed is zero.

Wind Directions Over Day

The fraction of time spent with the wind blowing from the various directions on an hourly basis. Values do not sum to 100% because the wind direction is undefined when the wind speed is zero.