Hartlepool Borough Council has reported “an increase in number of weever fish” and Tynemouth Volunteer Life Brigade has warned visitors of “reports of a large number” of the venomous fish.
Beachgoers have been advised to wear sandals or shoes when paddling and to shuffle feet in the sand rather than stamping.
A Tynemouth Volunteer Life Brigade said: “Be extra cautious in shallow, sandy areas.
“If stung, soak the affected area in hot (not scalding) water to help relieve pain, ensure the spines are not stuck in the foot and seek medical advice if required.”
A spokesperson for Hartlepool Council said: “In common with other areas along the coastline, we have seen an increase in the number of weever fish due to the recent warm weather.
“The fish lie under the sand on the shoreline and have venomous spines on their dorsal fins which when stood on puncture the skin on the foot – sometimes leaving the spine in the wound – causing a very painful sting.”