The week started with sunshine and highs in the upper 50s, but unfortunately, that was the lone highlight. Conditions are expected to continually deteriorate throughout the week.

And by the time trick-or-treaters put on their costumes Friday evening, it'll be downright cold.

And there could be snow on the ground.

"We're entering an active period where temps will be noticeably colder, and it'll be noticeably wetter," said Rich Leblang with the National Weather Service in Bismarck.

We'll get one more day of average temperatures today with highs near 50, which is where the thermometer is supposed to be this time of the year. And then the high temperatures will take significant drops the rest of the week.

"Wednesday night is when the real cold air comes down to stay," Leblang said. "And it stays into early next week or beyond."

Wednesday's high is expected to reach 40, Thursday's high into the 30s and Friday's high only into the upper 20s. There's also a chance of rain tonight and then snow Wednesday through Saturday.

"It looks like a wetter pattern for the next two weeks," Leblang said. "I don't see any monstrous snowstorms, just several chances to get episodes of light snow and flurries."

The Halloween forecast doesn't sound too favorable. The high will only reach into the upper 20s, and the high temperature typically happens around 3 or 4 in the afternoon, Leblang said. Then it starts cooling off. And snow is expected.

Friday's overnight low may dip to the upper teens and Saturday's overnight low is expected to be around 13.

The Halloween forecast resembles last year's weather, when the high was only 28 and the overnight low was 8 degrees.

(Reach reporter Mark Hanson at 250-8264 or mark.hanson@bismarck-tribune.com.)