There are locations that are known for a daily shower or summer storms. Pack accordingly so that the rain does not ruin your trip and create unnecessary hubbub trying to figure out plan B everyday. Consider packing plastic ponchos (they take up virtually no space so pack a few of them), an umbrella, and lightweight rain jacket with a hood. They make rain shoes as well that feel like tennis or hiking shoes and are quite comfortable – I bought a pair when taking a vacation to Niagara Falls because you walk through quite a bit of water and it can easily rain. Consider packing a waterproof disposable camera too as you may get some good pictures, even in the rain.