That out of 100%, there is a 15% chance of rain (if it helps think of it as 15 out of 100 points). So very unlikely it will rain
There is a 10% chance of any form of water falling from the sky.
A forecast that says, for instance, "there is a 10% chance of rain tomorrow," means that on 10 out of 100 days with weather conditions very similar to the conditions expected tomorrow, at least a trace of train has occurred. Some will disagree with this answer for various reasons. For the results of research that evaluated how understanding of percentage chance of precipitation varies around the world, see "A 30% Chance of Rain Tomorrow: How Does the Public Understand Probabilistic Weather Forecasts?," available as a PDF file via the URL http://www.mpib-berlin.mpg.de/en/mitarbeiter/gigerenzer/pdfs/RainFinal.pdf .
A 20 percent precipitation chance means that there is a 20 percent likelihood of measurable precipitation occurring in a specific area over a defined time period, typically 24 hours. This does not indicate how much rain may fall, but rather the probability that precipitation will happen at all. Essentially, it suggests that similar weather conditions have resulted in rain or snow 20 times out of 100 in the past.
Ten percent in precipitation typically refers to a forecast probability, indicating that there is a 10% chance of measurable rain occurring in a specific area over a defined period. It does not signify the actual amount of rainfall but rather the likelihood of precipitation happening. For example, if a weather report states a 10% chance of rain, it suggests that in similar weather conditions, rain would occur in 10 out of 100 instances.
99.9 CI means that there is a 99.9% chance the CI limits contains the value you are looking for.
It means that during the day there is a 15% chance of it raining tomorrow. That is very low and you will likely not see any rain, just a few clouds.
Probably not
That there will be no chance of rain or snow for that day
0.20 + 0.80*0.80
There is no 100% CHANCE of anything - If it is 100% it is 100% - raining or snowing
The probability that it will rain today and tomorrow is the multiplication of the probabilities of it raining both days. That is 0.6 X 0.4 = 0.24 So there is a 24% chance that it would rain both days.
It is possible. Your best chance though is to pay attention to when that precipitation is expected to happen.
There is a 10% chance of any form of water falling from the sky.
A forecast that says, for instance, "there is a 10% chance of rain tomorrow," means that on 10 out of 100 days with weather conditions very similar to the conditions expected tomorrow, at least a trace of train has occurred. Some will disagree with this answer for various reasons. For the results of research that evaluated how understanding of percentage chance of precipitation varies around the world, see "A 30% Chance of Rain Tomorrow: How Does the Public Understand Probabilistic Weather Forecasts?," available as a PDF file via the URL http://www.mpib-berlin.mpg.de/en/mitarbeiter/gigerenzer/pdfs/RainFinal.pdf .
It is 67%.
It is 1 - prob(it does not rain today and tomorrow)= 1 - prob(it does not rain today)*prob(it does not rain tomorrow) = 1 - [1- prob(it does rain today)]*[1 - prob(it does rain tomorrow)] = 1 - [1 - 0.8]*[1 - 0.5] = 1 - 0.2*0.5 = 1 - 0.1 = 0.9
A 30 percent chance of rain means there is a 3 in 10 chance it will rain in the specified area. It does not indicate the amount of rain that may fall, only the likelihood of precipitation occurring.