This report describes the typical weather at the Purdue University Airport (West Lafayette, Indiana, 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.
West Lafayette, Indiana has a humid continental climate with hot summers and no dry season. The area within 25 mi of this station is covered by croplands (98%).
The temperature typically varies from 47°F to 65°F and is rarely below 35°F or above 78°F.
The coolest hours of the day are from 2am to 9am with the coldest at 7am, at which time the temperature is below 54°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 57°F three days out of four.
The day has gained half its heat by 11am and lost it again by 8pm.
On October 12 the Sun rises at 7:55am and sets at 7:11pm.
Solar noon is at 1:33pm.
For reference, on the longest day of the year the Sun rises at 6:17am and sets at 9:20pm, while on the shortest day of the year it rises at 8:07am and sets at 5:24pm.
Astronomical twilight begins and ends 90 minutes before sunrise and after sunset at 6:25am and 8:41pm, respectively.
Nautical twilight begins and ends 59 minutes before sunrise and after sunset at 6:56am and 8:10pm, respectively.
Civil twilight begins and ends 27 minutes before sunrise and after sunset at 7:28am and 7:38pm, respectively.
Solar twilight begins and ends 37 minutes after sunrise and before sunset at 8:33am and 6:34pm, respectively.
The median cloud cover ranges from 34% (mostly clear) to 65% (partly cloudy).
At 1am, the clearest time of the day, the sky is clear, mostly clear, or partly cloudy 57% of the time, and overcast or mostly cloudy 42% of the time.
At 2pm, the cloudiest time of the day, the sky is overcast, mostly cloudy, or partly cloudy 57% of the time, and clear or mostly clear 43% of the time.
The sky is typically clearing in earnest by 8pm.
The clouds have typically started forming in earnest by 7am.
There is a 38% chance that precipitation will be observed at some point during the day.
The average measured liquid-equivalent quantity of precipitation is 0.030". Among only those days for which there is at least some measured precipitation, the average is 0.253" and the total rarely exceeds 0.495".
When precipitation does occur it is most often in the form of slight rain (46% of days with precipitation have at worst slight rain), thunderstorms (21%), and moderate rain (20%).
Precipitation is most likely around 7am and least likely around 3pm.
Either snow is exceptionally unlikely to fall at this location on October 12 or this station does not reliably report precipitation types.
The relative humidity typically ranges from 54% (mildly humid) to 84% (humid), rarely dropping below 34% (comfortable), or exceeding 97% (very humid).
The air is driest at 3pm, at which time the relative humidity is less than 65% (mildly humid) three days out of four; it is most humid at 6am, exceeding 77% (humid) three days out of four.
The dew point ranges from 42°F to 45°F with an average of 44°F.
For reference, comfortable indoor conditions should have a relative humidity between 30% and 50% with a dew point of less than 65°F.
Sustained wind speeds typically vary from 6 mph to 11 mph (light breeze to gentle breeze) over the course of the day.
The peak sustained wind speed typically occurs around 3pm and is rarely outside the range 6 mph to 17 mph (light breeze to moderate breeze).
The wind is most calm around 5am, rarely exceeding 12 mph (gentle breeze).
The wind is most often out of the west (16% of the time), south west (14% of the time), and south (13% of the time).