The warning said: “A band of rain is likely to become slow-moving across parts of southwest England during Monday.
“Given the recent wet weather and saturated ground, the likelihood of impacts is higher,” a spokesperson added.
The Met Office advised people to check if their properties could be at risk of flooding and if so, to prepare a flood plan and an emergency flood kit.
The spokesperson said people should amend travel plans if necessary.
They added: “Be prepared for weather warnings to change quickly: when a weather warning is issued, the Met Office recommends staying up to date with the weather forecast in your area.”