Most reliable way to gauge weather;
Get up, put arm out of caravan ( posh people ) or tent ( paupers like me
If arm WET, put on rain proof clothes.
If DRY, put on rain proof clothes. ( will probably rain later )
If arm gets blown back, first check if tent still OK, then put on rain proof clothes. ( High winds mean low pressure, low pressure usually means RAIN )
That's how we do it in Yorkshire.