Apex Wx

Overview: High pressure centered across Quebec will remain the dominant influence across northern Maine through Friday, while a slow-moving coastal low affects areas farther south. Dry continental air and light north to northeast flow will keep the Saint John Valley sunny, dry, and unusually mild for late September. After chilly mornings, strong daytime sunshine should allow temperatures to climb into the lower 70s today and Friday.

The coastal system will move somewhat closer to Maine by Saturday, spreading rain, thicker clouds, and stronger northeast winds into Downeast areas. Northern Maine should remain largely protected by high pressure, producing a pronounced north-to-south weather difference across the state. Clouds are likely to become more numerous in the Valley Saturday as Atlantic moisture circulates farther north, but current guidance continues to keep meaningful precipitation south of northern Aroostook County.

The northern extent of the coastal system’s moisture remains the principal forecast uncertainty. At present, however, the Saint John Valley is favored to remain mainly dry through Saturday, with temperatures easing only slightly as cloud cover increases.

Thursday: After another chilly start, abundant sunshine will produce a pronounced warm-up. Highs should reach the lower 70s, with light north to northeast winds. Tonight will be mostly clear and cool, with temperatures falling into the upper 30s to around 40°F. Patchy valley fog may develop late where winds become calm.

Friday: Mostly sunny to partly cloudy skies are expected as Fort Kent remains well north of the coastal system. Temperatures should again reach the lower 70s, making for an unusually mild late-September afternoon. North to northeast winds remain light. Clouds increase somewhat Friday night, but conditions should stay dry, with lows in the lower 40s. Northern Maine NWS guidance continues to show little or no precipitation.

Saturday: Clouds should become more numerous as the coastal low moves closer to Maine, but current guidance continues to favor a mainly dry day in the Valley. Expect partly sunny to mostly cloudy skies with highs in the upper 60s to around 70°F. Northeast winds may become somewhat more noticeable. Saturday night should remain mostly cloudy with lows in the lower to mid-40s. Any significant rain should remain well south of the Valley based on current guidance.

Sunday, September 27 – Wednesday, September 30

Overview: Following the mainly dry and mild weather of the preceding period, the slow-moving coastal low will remain the primary influence on Maine Sunday into Monday. Canadian high pressure to the north should continue to limit its reach into northern Aroostook County, but moisture circulating around the system may extend far enough north to bring increasing clouds and scattered showers to the Valley. Rainfall should remain intermittent and relatively light locally, with the wetter conditions concentrated farther south.

The coastal system should gradually weaken and pull away Monday night into Tuesday, allowing drier air and weak high pressure to return. Sunshine should become more prevalent Tuesday, with temperatures recovering after the cloudier start to the week. Mainly dry and somewhat milder weather should continue Wednesday as the SJV settles briefly between systems.

Attention then turns to the next disturbance approaching from the west late Wednesday night. Clouds should increase ahead of it, with a slight chance of showers developing toward Thursday morning. Overall, the period favors a brief unsettled interval Sunday night into Monday, followed by improving weather Tuesday and Wednesday.

Sunday: Partly sunny and mainly dry weather should continue through much of the day, with highs in the mid-60s. Clouds increase during the evening as moisture from the coastal system reaches farther north, with a chance of showers developing later Sunday night. Lows will fall into the lower 40s.

Monday: The coastal system will bring more clouds and a chance of occasional showers, although rainfall should remain scattered and light across the Valley. Highs will be in the lower 60s. Shower chances diminish Monday night as the system begins pulling away, with lows in the lower 40s.

Tuesday: Drier air returns as the coastal system loses its influence, bringing more sunshine and highs in the mid-60s. Tuesday night remains dry and partly cloudy, with lows in the lower to mid-40s.

Wednesday: Mostly sunny and somewhat milder weather continues, with highs in the mid- to upper 60s. Clouds increase Wednesday night ahead of the next disturbance, with a slight chance of showers developing after 4 AM. Lows will be in the upper 40s.

Weather Notice

Apex Wx forecasts are based on available observations, computer model guidance, and other meteorological data. Conditions and forecast guidance can change, and information displayed here may not reflect the latest official forecast or warning information. Always visit NWS Caribou for the latest official forecasts, watches, warnings, and advisories for northern Maine.

Apex Wx is a private weather information service unaffiliated with NOAA or the National Weather Service and operated by Joseph Becker. Dr. Becker earned a Certificate in Weather Forecasting from Penn State University and is a trained NWS SKYWARN Storm Spotter.

Credits

• Sun and Moon data from the U.S. Naval Observatory, with additional astronomical information from timeanddate.com.
• NOAA warning banner provided by WillyWeather.com.
• Through December 2026, additional archived Apex Wx weather data are available through the University of Utah's MesoWest.
• Current and archived Apex Wx weather data are available through Synoptic Data, the successor to MesoWest.
• Apex Wx logo by Joanna Becker © 2016. Visit Bushi and Brush Arts Dojo.

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