I'm a beginner and I have a generic time series and I want to know the probability that it reach a certain threshold in the future. For example, the time series is day average temperature and I want to know the probability that in the future there will be 40°.
I try to build a model (Holt, SES, ARIMA,...), fit past data and forecast future data, also calculate confindence intervals, but I didn't reach the point.
Is it right to say that if 40° is out the 95% intervals then his probability is less then 5%? But what if it is inside the interval? Imagine that in the previous days the temperature was 35,37,39,39,38... what is the probability that tomorrow there will be 40°?
P.S: I'm using software R.