Wednesday-Friday
Following Tuesday’s cool and cloudy weather, conditions across the St. John Valley will turn warmer and drier Wednesday and Thursday as high pressure becomes the dominant influence. Lingering moisture will support areas of dense river-valley fog Wednesday morning, with visibility locally dropping to one-quarter mile or less. The fog should dissipate as temperatures rise and daytime mixing develops, leaving a dry but generally cloudy day. Patchy fog may redevelop in sheltered valleys Wednesday night.
Thursday will bring the most noticeable change. Southwest winds will draw considerably warmer air into northern Maine, pushing afternoon temperatures into the 70s. Winds will also strengthen as high pressure moves away and low pressure passes through Canada, with afternoon gusts potentially reaching 25 mph. Morning valley fog should give way to partly sunny skies.
Conditions deteriorate Thursday night into Friday as a cold front approaches from the northwest. Clouds will increase first, followed by rain spreading across the County. Friday currently has the highest rain probability of the seven-day period, although rainfall amounts should remain relatively modest. As the front crosses the region, winds will shift and cooler, drier Canadian air will begin arriving. Rain should diminish Friday evening, with partial clearing developing overnight as temperatures fall sharply into the upper 30s.
Saturday-Tuesday
Saturday will provide a distinctly cooler start to the weekend as high pressure builds behind Friday’s front. Sunshine should return across the Valley, although northwest winds may remain somewhat noticeable during the day. Winds will diminish Saturday night as the high settles closer to northern Maine. Clear skies, dry air, and light winds will favor strong nighttime cooling, with temperatures falling to around 30°F and potentially lower in sheltered locations. Frost and freezing conditions are possible.
Sunday begins mostly sunny and seasonably cool, but the quiet weather will not last. Clouds will increase during the afternoon as another disturbance and frontal system approach from the west. Showers become more likely Sunday night and should continue at times Monday as the system crosses Aroostook County. This does not presently appear to be a major rainfall event, but another period of damp weather is likely.
Showers should diminish Monday evening as the system moves east and another surge of cooler Canadian air follows. Temperatures will again fall toward 30°F Monday night. Tuesday should turn drier behind the departing system, although afternoon temperatures may struggle to reach much beyond 50°F. Partly cloudy and cold conditions are expected Tuesday night, with lows generally in the lower 30s.
Looking Ahead: October 7-13
The Climate Prediction Center indicates equal chances for temperatures and favors above-normal precipitation across northern Maine for October 7-13. Equal chances does not specifically forecast normal temperatures; rather, there is no clear preference for above-, near-, or below-normal readings during the period. The precipitation outlook suggests a wetter-than-normal week overall, although it does not indicate when individual rain events might occur. Typical early-October conditions in the Valley feature highs in the mid- to upper 50s and lows in the mid- to upper 30s.
Daily Forecast Summary
Wednesday: Patchy dense fog during the morning, then mostly cloudy. Highs in the upper 60s. Southwest winds around 5 mph.
Wednesday Night: Partly cloudy during the evening, becoming mostly clear. Patchy valley fog possible. Lows in the upper 40s. Southwest winds around 5 mph.
Thursday: Patchy morning fog, then partly sunny and warmer. Highs in the mid-70s. Southwest winds 10-15 mph with gusts up to 25 mph.
Thursday Night: Mostly cloudy with a 20% chance of rain. Lows in the mid-50s. Southwest winds 5-10 mph.
Friday: Rain likely. Highs in the mid-60s. West winds 5-10 mph. Chance of rain 70%.
Friday Night: Mostly cloudy with a 50% chance of rain during the evening, becoming partly cloudy after midnight. Cooler, with lows in the upper 30s.
Saturday: Sunny and cool. Highs in the upper 50s.
Saturday Night: Clear and cold. Lows around 30°F, with colder readings possible in sheltered locations.
Sunday: Mostly sunny during the morning, becoming mostly cloudy during the afternoon. Highs in the upper 50s.
Sunday Night: Mostly cloudy with a 50% chance of showers. Lows in the upper 30s.
Monday: Mostly cloudy during the morning, becoming partly sunny. A 50% chance of rain showers. Highs in the mid-50s.
Monday Night: Partly cloudy with a 40% chance of rain showers during the evening. Cold, with lows around 30°F.
Tuesday: Partly sunny and cool. Highs around 50°F.
Tuesday Night: Partly cloudy and cold. Lows in the lower 30s.
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.
