Morning low temperatures have been very mild so far this month in Portland. Only one observed low of the last 13 (the morning of the 2nd) has been cooler than average, the rest have been warmer than average. Typically, more rural lowland spots like Hillsboro would have already had their first frost (low temperature at or below freezing), but it hasn't happened yet. It might next week! A cooler air mass and clearing skies could usher in morning temperatures in the 30s. | FOX 12 Weather