Farmers markets can be extremely weather dependent. You will need to learn more about the location and venue that each market will be operating in to know if the weather will impact the market.
Local farmers markets typically watch the weather very closely to see if they can still operate despite potentially inclement weather. Since these markets make up a great deal of the income for many local farmers, it is important for them to stay open as often as possible.
Still, on some occasions, it is necessary for the market to close. They often are made up of collections of small outdoor tents housing different businesses. Wind can be especially damaging to these booths. As the canvas tents are wind resistant, the impact will likely be more on the produce and goods sitting out at the market. Strong winds can damage the foods that the farmers intend to sell and make it impossible for them to keep their booths open.
Similarly, rain can create problems. Pools of water can create muddy market conditions that are especially difficult for visitors to navigate. Heavy rains can also collect on tents, making the structures heavier and susceptible to water pooling on the roof. These conditions are far from ideal and sometimes force farmers markets to choose to close.
Bad weather can also lead to low attendance for farmers markets. Most markets try to only operate during warmer seasons to ensure that visitors are comfortable while perusing the booths. However, unexpected cold snaps can create big problems. These sudden cold spells can also make it impossible for certain crops to grow properly, and farmers might have limited stock as a result.
If you are planning to attend a farmers market, it is best to check the weather first to see if you might run into problems. You can typically reach out to the market organizers and make sure they are staying open if the weather looks questionable.