This report describes the typical weather at the London Heathrow Airport (London, United Kingdom) weather station over the course of an average November 15. It is based on the historical records from 1974 to 2012. Earlier records are either unavailable or unreliable.
London has a mild humid temperate climate with warm summers and no dry season. The area within 25 mi of this station is covered by croplands (60%), built-up areas (35%), and grasslands (4%).
The temperature typically varies from 44Â°F to 50Â°F and is rarely below 35Â°F or above 57Â°F.
The coolest hours of the day are from midnight to 9am with the coldest at 5am, at which time the temperature is below 49Â°F three days out of four.
The warmest hours of the day are from 11am to 4pm with the hottest at 2pm, at which time the temperature is above 47Â°F three days out of four.
The day has gained half its heat by 11am and lost it again by 7pm.
On November 15 the Sun rises at 7:20am and sets at 4:12pm.
Solar noon is at 11:46am.
For reference, on the longest day of the year the Sun rises at 4:44am and sets at 9:23pm, while on the shortest day of the year it rises at 8:05am and sets at 3:55pm.
Astronomical twilight begins and ends 117 minutes before sunrise and after sunset at 5:23am and 6:08pm, respectively.
Nautical twilight begins and ends 78 minutes before sunrise and after sunset at 6:02am and 5:29pm, respectively.
Civil twilight begins and ends 36 minutes before sunrise and after sunset at 6:44am and 4:48pm, respectively.
Solar twilight begins and ends 53 minutes after sunrise and before sunset at 8:13am and 3:18pm, respectively.
The median cloud cover is 87% (mostly cloudy) and does not vary substantially over the course of the day.
On average, the sky is clear or mostly clear 24% of the time, partly cloudy 15% of the time, and mostly cloudy or overcast 56% of the time.
There is a 70% chance that precipitation will be observed at some point during the day.
When precipitation does occur it is most often in the form of moderate rain (71% of days with precipitation have at worst moderate rain), slight rain (9%), drizzle (8%), and heavy rain (7%).
Precipitation is observed with more or less equal probability throughout the day.
Either snow is exceptionally unlikely to fall at this location on November 15 or this station does not reliably report precipitation types.
The relative humidity typically ranges from 76% (humid) to 90% (very humid), rarely dropping below 62% (mildly humid), or exceeding 98% (very humid).
The air is driest at 2pm, at which time the relative humidity is less than 84% (humid) three days out of four; it is most humid at 5am, exceeding 86% (very humid) three days out of four.
The dew point ranges from 41Â°F to 43Â°F with an average of 42Â°F.
For reference, comfortable indoor conditions should have a relative humidity between 30% and 50% with a dew point of less than 65Â°F.
The wind speed is 8 mph (gentle breeze) on average and is rarely outside the range 3 mph to 15 mph (light air to moderate breeze). The wind speed does not vary substantially during the course of the day.
The wind is most often out of the south west (21% of the time), west (19% of the time), south (18% of the time), and north (10% of the time).