FiveThirtyEightScience published an interesting article this week on using statistics to determine which parts of the US had the most and least predictable weather.  They used a combination of ten different variables including max and min temperature, precipitation, winds and severe weather to determine how changeable each value was.  The areas with the highest amount of variability were identified as the areas that were least predictable.  The city with the least predictable weather in the US?  Rapid City, SD.  You can see the map of the US below.  In general, in the Southeast southern Florida is the most predictable and northern Alabama is the least predictable.  You can read about how they did the calculations at https://fivethirtyeight.com/features/which-city-has-the-most-unpredictable-weather/

Based on NWS data
Based on NWS data