It is good weather for picnics right now.
You should always remove your shoes before putting your feet on a picnic blanket. Not only do people sit on picnic blankets, but they put food on them. Resting shoes on a picnic blanket is like putting your shoes on the dinner table or even a dinner plate.
Many people who wear shoes at home will remove their shoes before sitting on a picnic blanket, but it is amazing that some people will keep their dirty shoes on.