Apex Wx

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Overview: The improving trend from Sunday continues into Labor Day as high pressure provides abundant sunshine, dry conditions, and a pleasantly warm afternoon across Fort Kent and the Valley. A weak disturbance and cold front from Quebec will cross northern Maine tonight into Tuesday, bringing additional clouds and perhaps an isolated shower. Little moisture accompanies the system, so the more noticeable change Tuesday will be cooler temperatures and a northwest breeze rather than significant rainfall.

High pressure briefly returns Tuesday night, with clearing skies and lighter winds allowing temperatures to fall sharply. Colder portions of the County may fall into the low to mid-30s, allowing some frost to develop, while much of the Valley should remain somewhat milder. Patchy valley fog may also develop where winds become sufficiently light. Wednesday begins mainly dry, but the next, stronger system will approach from the west during the day. Clouds will increase and southerly winds will develop, with rain spreading into the region Wednesday evening and becoming widespread overnight. Confidence continues to increase in a wetter and gustier period Wednesday night into Thursday.

Labor Day: A very pleasant holiday is expected as high pressure provides abundant sunshine, dry conditions, and comfortable humidity. Highs should reach the lower to mid-70s, with northwest winds around 5–10 mph, occasionally higher. Clouds increase tonight as a weak disturbance approaches, with a chance of showers developing after midnight. Northwest winds remain around 5–10 mph, with lows in the mid-40s.

Tuesday: A weak frontal passage brings a noticeably cooler day. Morning clouds and perhaps an isolated shower should give way to increasing sunshine, with highs generally in the lower to mid-60s. Northwest winds increase to around 10–15 mph. Tuesday night should become mostly clear before some clouds return late. Winds diminish, with lows generally in the upper 30s to around 40°F across the Valley. Colder portions of northern Aroostook County could fall into the low to mid-30s, with some frost development possible. Patchy valley fog may also develop.

Wednesday: A dry start should give way to increasing clouds as a stronger system approaches from the west. Most of the daytime period may remain dry, with highs in the mid-60s and winds becoming southerly around 5–15 mph. Rain develops later Wednesday and becomes widespread Wednesday night, potentially moderate at times. Southerly winds will also strengthen overnight. Temperatures should remain relatively mild, with lows in the lower to mid-50s.

Thursday, September 10 – Sunday, September 13

Overview: Following the wetter and windier period expected Wednesday night into Thursday, conditions should improve fairly quickly as the system moves east into Canada and the Maritimes. Rain Thursday morning should become more scattered and showery before tapering off, while winds shift to the west and northwest and become gusty behind the front. Cooler and drier air will then spread into Fort Kent and the Valley Thursday night.

Friday will be noticeably cooler, with lingering clouds gradually giving way to increasing sunshine as high pressure builds toward northern Maine. The air mass will begin moderating Saturday, bringing a pleasant start to the weekend with sunshine, low humidity, lighter winds, and temperatures recovering toward 70°F. By Sunday, high pressure will shift east as a weak disturbance approaches from Canada. Most of the day should remain dry, although a few showers may develop later and linger into Sunday evening before conditions begin improving overnight.

Thursday: A rainy and increasingly breezy start is expected as the Canadian low and associated frontal system move through the region. Periods of rain should continue during the morning, becoming more showery with time. An isolated thunderstorm cannot be ruled out. Highs should reach the upper 60s to around 70°F, depending on frontal timing. Winds will shift from south or southwest to west and northwest behind the front, with gusts potentially reaching 30–35 mph. Showers diminish Thursday evening, followed by partly cloudy and cooler conditions overnight. Lows should fall into the lower 40s.

Friday: A distinctly cooler day follows the frontal passage. Lingering clouds gradually give way to increasing breaks of sunshine as high pressure begins building toward northern Maine. Highs reach the upper 50s to around 60°F, with a northwest breeze making the change from Thursday particularly noticeable. Friday night turns mostly clear as winds diminish, with lows around 40°F and locally colder conditions possible in sheltered Valley locations.

Saturday: High pressure provides a quiet start to the weekend. Mostly sunny to partly cloudy skies and dry conditions are favored, with temperatures recovering into the mid- to upper 60s. Winds become considerably lighter than Thursday and Friday. Saturday night remains mainly clear and cool, with lows in the lower to mid-40s and patchy fog possible where winds become light.

Sunday: High pressure remains influential, although it begins shifting east as the next weak disturbance approaches from Canada. Most of the day looks dry, with a mixture of sunshine and clouds and highs in the lower 70s. A slight chance of a shower develops later in the day, with relatively light winds. A few showers may linger into Sunday evening before skies begin clearing overnight. Temperatures fall into the upper 40s to around 50°F, with west winds around 5–10 mph.

The latest outlook favors near-normal temperatures and above-normal precipitation across northern Maine and the Saint John Valley. Broad ridging is expected across much of the central and eastern United States, while troughing over eastern Canada may temper the warmer pattern across northern New England. Mid-September climatology across the Valley generally features daytime highs in the mid-60s and overnight lows in the lower to middle 40s, with temperatures gradually declining through September.

Outlooks updated 7-9 AM weekdays & 8-10 AM weekends and holidays. Long range outlooks indicate broader temperature and precipitation trends rather than precise day-to-day forecasts.

Updated every 3-6 hours from NWS Caribou

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, PhD. 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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