St. John Valley weather, July 15-21, 2026

Joseph E. Becker, Special to The County
1 day ago

Wednesday, July 15-Friday, July 17

Fortunately, despite a number of favorable ingredients, the severe weather threat did not materialize yesterday. A cool, upper-level low to the north over Quebec will dominate the Valley’s weather through the end of the week.

Today, a cold front will move across Maine this morning, bringing periods of light showers as it pushes toward the Downeast coast. The showers will gradually end from north to south through the morning, and thunderstorms are not expected during this time. Rainfall amounts will generally be light, with most locations receiving less than 1/10-inch.

Patchy smoke from Canadian wildfires may linger near the ground across northern Maine through around midday. While the smoke is not expected to be as dense as it was yesterday, it may still reduce visibility in a few areas before improving this afternoon. Clouds will increase through the day as another cold front approaches, with afternoon highs reaching the middle to upper 70s across much of the region. West winds will increase to 10 to 15 mph, with gusts approaching 30 mph, making for a breezy afternoon.

Although most communities will remain dry, a few isolated showers or thunderstorms may develop late this afternoon and early evening. Coverage will remain limited, with only about a 30% chance of precipitation.

Thursday will be noticeably cooler, with highs generally in the upper 60s to around 70 degrees under a mix of sunshine and clouds. A brisk west wind of 10 to 15 mph, with gusts up to 25 mph, will continue. There is a slight chance of an afternoon shower or thunderstorm, but many locations will stay dry. While severe weather is not expected, the cool air aloft could allow a stronger storm to produce small hail.

Cooler weather will persist into Friday as the upper-level area of low pressure remains north of the region. Skies will be mostly sunny, with afternoon highs in the lower to middle 70s. Northwest winds of 10 to 15 mph, with gusts up to 25 mph, will keep conditions feeling cool. Overnight lows Thursday and Friday nights will fall into the lower to middle 50s, with some of the colder northern valleys dipping into the upper 40s.

Saturday, July 18-Tuesday, July 21

A cooler weather pattern will remain in place through the weekend as an upper-level area of low pressure lingers north of the region. Daytime temperatures will generally be near seasonal averages, while nighttime temperatures will be cooler than normal.

Friday will likely be the coolest day, especially across northern Maine, where afternoon highs may remain in the upper 60s. Overnight lows from Friday night through Saturday night will fall into the lower to middle 50s for most areas, with some of the colder northern valleys dropping into the upper 40s.

Saturday will be mostly sunny and pleasant, with afternoon highs reaching the upper 70s. West winds will be light, generally around 5 to 10 mph. Clouds will gradually increase Saturday night, and there will be a slight chance of showers after midnight as the next weather system approaches.

On Sunday, an area of low pressure will track across southern Maine, bringing a chance of showers and a few afternoon thunderstorms, particularly across eastern portions of the region. Many locations will still experience extended periods of dry weather, with highs in the middle to upper 70s. Any showers or thunderstorms will gradually diminish Sunday evening, followed by partly cloudy skies overnight.

High pressure will briefly build into the region on Monday, providing mostly sunny skies and warmer temperatures. Afternoon highs will climb into the lower 80s, making Monday the warmest day of the period. Clouds will increase Monday night, along with a chance of showers ahead of the next approaching weather system. Lows fall into the lower 50s across the SJV.

A cold front will move toward the region on Tuesday, bringing increasing clouds along with scattered showers and thunderstorms. Afternoon highs will range from the upper 70s to around 80 degrees. Showers and thunderstorms will become more numerous Tuesday night as the cold front crosses the area, with additional showers possible into Wednesday as a secondary cold front approaches. Lows Tuesday night fall into the mid-to-upper 50s.

Daily Forecast

Today: Mostly sunny this morning, then partly sunny with isolated thunderstorms this afternoon. Patchy smoke. Highs in the mid-70s. West winds 10 to 15 mph with gusts up to 30 mph. Chance of precipitation 20 percent. Tonight: Partly cloudy in the evening, then clearing. Lows in the lower 50s. West winds 10 to 15 mph. Gusts up to 30 mph in the evening.

Thursday: Mostly sunny with a 40 percent chance of showers. Highs in the upper 60s. West winds 10 to 15 mph with gusts up to 30 mph. Thursday Night: Partly cloudy. Lows in the upper 40s. West winds 10 to 15 mph with gusts up to 30 mph.

Friday: Sunny. Highs in the lower 70s. Northwest winds 10 to 15 mph with gusts up to 30 mph. Friday Night: Mostly clear. Lows around 50.

Saturday: Mostly sunny. Highs in the mid-70s. Saturday Night: Mostly cloudy with a chance of showers. Lows in the lower 50s. Chance of rain 40 percent.

Sunday: Mostly sunny. A chance of showers in the morning. Highs in the mid-70s. Chance of rain 40 percent. Sunday Night: Partly cloudy in the evening, then becoming mostly clear. Lows in the lower 50s.

Monday: Mostly sunny. Highs in the upper 70s. Monday Night: Mostly cloudy. A chance of showers after midnight. Lows in the mid-50s. Chance of rain 30 percent.

Tuesday: Partly sunny with a chance of showers. Highs in the upper 70s. Chance of rain 50 percent. Tuesday Night: Mostly cloudy with showers and thunderstorms likely. Lows in the mid- 50s. Chance of rain 50 percent.

Weather Notice: The weekly forecast, by UMFK Professor Joseph E. Becker, is based on available computer models and data and may not reflect current conditions or later forecast updates. Check The County.me or the National Weather Service Caribou, Maine for the most recent weather information for the Saint John Valley.