The average price for gas in Massachusetts was $3.909 a gallon in the latest weekly AAA survey, the highest price ever for September and 10 cents higher than last week’s average, AAA Southern New England said Monday.

Massachusetts prices have risen 17 cents a gallon over the past month, AAA Southern New England added.

The current national average is $3.86 a gallon. A year ago at this time, the Massachusetts average price was $3.62, AAA Southern New England said.

AAA’s weekly surveys focus on self-serve regular unleaded gas.