Carlos Guzman Hernandez, a local politician in the central state of Hidalgo, was found dead of hypothermia after his car failed on the road.
In the northeastern border city of Matamoros, an old woman was killed by a fire when a stove she lit burned her home. In the eastern coastal state of Veracruz, a three-year-old girl died of carbon monoxide poisoning. Her mother was in serious condition.
On Saturday, Mexican Health Minister Jose Angel Cordova Villalobos had reported nine confirmed deaths due to the freezing weather.
The National Meteorological Service said temperatures in the past week, which hit minus 11 degrees Celsius in some northern states, were the lowest since 1886.
It said the cold weather will last at least two more days.
The southern states and the Gulf of Mexico regions, which are traditionally warmer, are also experiencing strong winds and cold.
Also on Monday, El Salvador issued a yellow alert due to high winds and cold weather.
The bad weather has triggered four power cuts, and partially damaged 20 homes and one public building in El Salvador.
The nation's meteorology service is predicting winds of up to 60 km per hour and minimum temperatures of 4 degrees Celsius in some regions.
It has also warned of strong winds within 48 hours that could hit the country's shipping industry.
Editor: Anne Tang