Rock Hill region weather is changing, forecasters say. What to expect for Halloween.

Say goodbye to the warm, dry weather that has blanketed the Rock Hill area for the past few weeks. Cooler and wetter conditions are on the way, forecasters says.

The wetter pattern is expected to last into the weekend, but it appears that rain will end in time for Sunday’s Halloween trick-or-treating, experts say.

Rock Hill’s daily high temperatures have been above average on 20 of the first 24 days in October. Meanwhile, about two-thirds of an inch of rain has fallen at Rock Hill’s airport. That’s about 35 percent of what normally falls in the first three-plus weeks of October.

But across the United States, weather patterns are turning more active.

A series of strong storm systems has battered the West Coast in recent days, and a nor’easter storm is forecast to move up the Mid-Atlantic coast on Tuesday and Wednesday.

Part of that changed pattern will be obvious in the Carolinas, forecasters say.

A few showers crossed the Rock Hill area Monday morning, with additional showers and thunderstorms expected Monday evening with the passage of a cold front.

In the wake of the front, cooler temperatures are expected Tuesday and Wednesday.

National Weather Service meteorologist Jeffrey Taylor says high pressure will build into the Carolinas for a few days, bringing what Taylor called “near normal” temperatures. That means highs around 70 or 71 degrees.

The next big weather-maker, Taylor says, will arrive Thursday. He said a large trough (or dip in the jet stream) will move into the eastern United States. Low pressure is expected to develop, and that will translate into a cool, rainy day Thursday.

And what about the weekend? A number of church and other groups have autumn and Halloween festivals scheduled, especially Saturday.

Taylor said showery conditions could last into Friday and Saturday, although it is too early to know how numerous or heavy that rainfall might be.

One thing is certain, Taylor said.

“Temperatures are expected to start out well-below normal on Thursday and remain below-normal through the weekend,” Taylor said.

Taylor said by later Sunday, high pressure is expected to be building into the area. He said that will bring an end to showers and clear the skies.