However, if you are a more advanced forecaster, you can check the weather map to see where there is a cold front.
If the atmosphere is also very humid, then you may see rain. The weather map will also tell you where there high or low pressure centers. None of these methods needs special knowledge or technology
On the other hand, if there are clouds in the sky, they will reflect the sun's rays, and this will lower the temperature. At night, the opposite happens. These are conclusions that can be reached with just a little common sense.