Why does it rain more at night?

It seems from my experience that it tends to rain more at night. why is that? sure it is colder at night — but what does that have to do with rain?

I searched and found an answer on Ask a Scientist by that I am not sure I agree with:

Some types of precipitation are diurnally affected, such as thunderstorms that result from surface heating. These storms usually form in the afternoon, and may extend well into the nighttime, before dissipating in the early morning. Other thunderstorms associated with frontal movements may occur at any time, when conditions are favorable.

The heavy rains you mention usually occur in California as a result of
storms moving onshore from the Pacific ocean. But time of day usually is not a factor in these precipitation events. These storms may seem to occur during the evening and night, because people tend to be at home more at those times, and are more aware of adverse weather conditions. During the daytime, when they are at work, these rain storms may be less noticed.

It seems it really does rain more at right (at least in California) and that I’d actually notice it more in the day (because I am awake and sit by a window).


10 thoughts on “Why does it rain more at night?

  1. Aaron

    I heard that air presure decreases at night, perhaps that is a factor that makes it rain more at night.

  2. Emilie K.

    Ok, so I am no scientist. During the day, the sun aids in the evaporation of excess moisture in the air. At night, there is no sun, so excess moisture builds up in the clouds and dumps rain at night… This is my best guess.

  3. hiya

    This is a pretty simple answer but isn’t it just because it’s colder, so the evaporated water becomes water, and falls ?

  4. Gabe

    Simple answer is warm air holds more water molecules than cooler air. When temp lowers at night, relative humidity tends to increase because the air cannot hold more moisture. It eventually reaches the dewpoint (where the temp = dewpoit or basically 100% relative humidity). Between 90-100% relative humidity, you’ll start seeing ‘fog’ or just the water in the air.
    So because cooler air cannot hold as much moisture, and it cools off at night, you’ll encounter precipitation at night more often than during the day.
    Other factors come into play, this is a simplistic answer.

  5. Respectthedude

    I’ve notice that too!
    It’s not rather if it’s raining at night or not but the timing of the front which the start happens at night and if it’s moisture rich it will last thru the day too.
    In California (Northern and Southern) most fronts are not the convective kind that needs daytime heating until spring especially if it’s a wet spring vs a dry spring when dry springs convective fronts peel themselves apart in a stuck cycle leading to further dryness.
    IFor some reason the initial start of most fronts to enter you’re area tends to be either A: In the middle of the night or B: Morning hours effecting the morning rush hour which I think has to do with higher humidity levels. At night it’s more humid. 80-90%
    The storms that DO effect the evening rush hour are usually the convective type cold fronts producing a heavy burst of rain/sleet or snow screwing up rush hour. That has more to do with daytime heating effects and how close to a water source you are.
    Washington DC and Baltimore Maryland for example in the late winter towards spring (Late February-March) can easily get those type of cold front convective systems that screw up the evening commute bringing an hour or two burst of heavy snow creating dozens of fender benders and jackknifed trucks.
    This winds up leading to school closings the next morning especially if they didn’t use up any snow days during that winter which then they start using them up like mad as if competing with each other on who can use up the most snow days!

  6. Respectthedude

    BTW: That supposed scientists is full of BS which is why he his not helpful to you. What he said is a *kind* way that you are a nutcase for even mentioning it which I find quite rude indeed.
    Most scientists have a mental box around them that thinks in order to have valid results they have to be preformed in a controlled lab but in reality most discoveries cannot be done in a lab and are done quite by accident after a lot of failures.
    scientists tend to get very smug with themselves and view other people as inferior peasants and often do their own stereotyping even though they claim not to.

  7. Respectthedude

    I think you’re on to something too but the speed of the storm plays a role on if the rain will last all day.
    Storms that seem to rain throughout the daytime actually start in the middle of the night and have so much moisture it takes that long to unleash it especially if the front is slow.
    Convective type systems tend to effect the evening commute more due to daytime heating effects. See my post about Washington DC and Baltimore Maryland spring storms.

  8. raje

    can you be sure it rains more at night ?
    why not make your own rain gauge (also known as an udometer, pluviometer, or an ombrometer) and find out the truth.
    take readings at fixed timings,
    plot your data on a simple graph paper,
    be prepared for a surprise !!!


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