This report describes the typical weather at the Riverside Municipal Airport (Riverside, California, United States) weather station over the course of an average October 19. It is based on the historical records from 1998 to 2012. Earlier records are either unavailable or unreliable.
Riverside, California has a cold semi-arid steppe climate. The area within 25 mi of this station is covered by shrublands (66%), forests (19%), and built-up areas (12%).
The temperature typically varies from 56°F to 80°F and is rarely below 50°F or above 92°F.
The coolest hours of the day are from midnight to 9am with the coldest at 7am, at which time the temperature is below 58°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 71°F three days out of four.
The day has gained half its heat by 11am and lost it again by 8pm.
On October 19 the Sun rises at 6:58am and sets at 6:10pm.
Solar noon is at 12:34pm.
For reference, on the longest day of the year the Sun rises at 5:39am and sets at 8:04pm, while on the shortest day of the year it rises at 6:51am and sets at 4:45pm.
Astronomical twilight begins and ends 83 minutes before sunrise and after sunset at 5:34am and 7:33pm, respectively.
Nautical twilight begins and ends 54 minutes before sunrise and after sunset at 6:03am and 7:04pm, respectively.
Civil twilight begins and ends 25 minutes before sunrise and after sunset at 6:33am and 6:35pm, respectively.
Solar twilight begins and ends 34 minutes after sunrise and before sunset at 7:32am and 5:36pm, respectively.
The median cloud cover ranges from 1% (clear) to 12% (mostly clear).
At 9pm, the clearest time of the day, the sky is clear, mostly clear, or partly cloudy 78% of the time, and overcast or mostly cloudy 14% of the time.
At 8am, the cloudiest time of the day, the sky is overcast, mostly cloudy, or partly cloudy 34% of the time, and clear or mostly clear 62% of the time.
The sky is typically clearing in earnest by 1pm.
The clouds have typically started forming in earnest by 4am.
There is a 9% chance that precipitation will be observed at some point during the day.
The average measured liquid-equivalent quantity of precipitation is 0.013". Among only those days for which there is at least some measured precipitation, the average is 0.091" and the total rarely exceeds 0.168".
When precipitation does occur it is most often in the form of slight rain (62% of days with precipitation have at worst slight rain), moderate rain (16%), heavy rain (11%), and thunderstorms (10%).
Precipitation is most likely around 6am and least likely around 9pm.
There is a 7% chance that there will be snow on the ground. The average snow depth is 0.9". The snow depth is deeper than 0.9" one year in four and deeper than 0.9" one year in ten.
The relative humidity typically ranges from 36% (comfortable) to 76% (humid), rarely dropping below 15% (very dry), or exceeding 93% (very humid).
The air is driest at 2pm, at which time the relative humidity is less than 49% (comfortable) three days out of four; it is most humid at 5am, exceeding 66% (mildly humid) three days out of four.
The dew point ranges from 44°F to 49°F with an average of 47°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 2 mph to 9 mph (light air to gentle breeze) over the course of the day.
The peak sustained wind speed typically occurs around 5pm and is rarely outside the range 6 mph to 13 mph (light breeze to moderate breeze).
The wind is most calm around 1am, rarely exceeding 4 mph (light breeze).
The wind is most often out of the west (21% of the time). The wind is least often out of the south west (2% of the time), south (2% of the time), south east (4% of the time), and north (4% of the time).