OTTAWA -- Ottawa motorists are being advised to fill up the gas tank today, ahead of the switch to summer gasoline blend.

President of Canadians for Affordable Energy Dan McTeague says gas prices will rise 5 cents a litre on Sunday in Ottawa and across Ontario.

McTeague says stations will switch to their summer gasoline blend, which is more expensive. Refiners switch to the pricier summer-blend gasoline in April.

According to Ottawagasprices.com, the average price of gasoline in Ottawa is $1.21 a litre. Several stations in Ottawa were selling gasoline for $1.249 a litre on Saturday afternoon.