The Massachusetts unemployment rate edged upward for the third straight month, climbing to 6.5 percent in September, the Massachusetts Executive Office of Labor and Workforce Development reported Thursday.

The state’s jobless rate had been at a recent low of 6 percent in June, but rose to 6.1 percent in July and 6.3 percent in August, before it rose again last month. The trend was anticipated by economists, who said a global economic slowdown, uncertainty about US tax policy, and other factors, such as rising gasoline prices, have contributed to a climate of uncertainty and slowed hiring.