Apex Wx

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Overview: The slow-moving upper-level system responsible for the recent wet and unsettled weather will continue moving into the Maritimes this weekend. Its lingering influence will keep Fort Kent and the Valley cool and somewhat unsettled Saturday, with considerable cloud cover, scattered showers, and a noticeable north to northeast breeze. The day will not be a washout, however, with substantial dry periods expected.

Conditions improve considerably Saturday night into Sunday as high pressure from the west and drier air build into northern Maine. Sunday should feature more sunshine, low humidity, and seasonable temperatures, followed by a cool night with possible Saint John River valley fog. Labor Day is shaping up to be the best day of the holiday weekend, with abundant sunshine, comfortable humidity, and temperatures warming into the lower to mid-70s. Clouds may begin increasing Monday night ahead of a weak cold front approaching from Quebec.

Saturday: A cool and somewhat unsettled start to the holiday weekend. Considerable cloud cover will accompany scattered showers, especially from late morning through the afternoon, although substantial dry periods are expected. Highs should reach the mid to upper 60s, with north to northeast winds around 10–15 mph and occasionally higher gusts. Showers diminish this evening as drier air arrives. Saturday night should become partly to mostly cloudy and cool, with northerly winds gradually easing and lows in the mid- to upper 40s.

Sunday: A much-improved day as the departing upper low moves farther into the Maritimes and high pressure takes greater control. Skies should range from mostly sunny to partly cloudy, with dry conditions, low humidity, and highs in the mid to upper 60s. North winds around 5–10 mph, occasionally higher early, should gradually ease. Sunday night will be mostly clear and cool with light winds and lows in the lower to mid-40s. Patchy Saint John River valley fog may develop late.

Labor Day: The best weather of the holiday weekend is expected as high pressure provides abundant sunshine, dry conditions, and comfortable humidity. Temperatures should respond to the moderating air mass by climbing into the lower to mid-70s. Light northwest winds should increase to around 5–10 mph during the day. Clouds may begin increasing Monday night ahead of a weak cold front approaching from Quebec, with a chance of showers developing late. Lows should settle into the upper 40s to around 50°F.

Tue. Sep. 8 - Fri. Sep. 11

Overview: A weak cold front from Quebec will cross northern Maine early Tuesday, possibly bringing a brief shower before cooler and drier air returns. Tuesday afternoon and much of Wednesday should be mainly dry, with high pressure providing a short break between systems. Clearer skies and light winds Tuesday night may allow temperatures to fall near 40°F in colder Valley locations, with patchy valley fog possible.

The pattern turns more unsettled Wednesday night as a stronger disturbance approaches from the west. Rain should become more widespread overnight and continue as showers Thursday, with an isolated thunderstorm possible depending on available instability. The system pulls away Thursday night, allowing cooler and drier northwest flow to return. Friday should trend noticeably cooler but increasingly dry as high pressure begins building toward northern Maine. At present, the greatest uncertainty concerns the timing and intensity of Thursday's system and whether sufficient instability develops for thunderstorms.

Tuesday: A weak cold front crossing northern Maine may produce an early shower, but most of the day should be dry. Clouds should give way to increasing sunshine with noticeably cooler and less humid conditions. Highs should reach the lower to mid-60s, with winds becoming northwest around 5–10 mph. Tuesday night should be mostly clear and chilly with light winds. Lows should fall into the upper 30s to lower 40s, with patchy river valley fog possible late. Current northern Maine guidance supports the cooler trend behind the front.

Wednesday: A cool and mainly dry start is expected before the next weather system approaches. Sunshine should gradually give way to increasing clouds, with highs in the lower to mid-60s and generally light winds becoming southerly or southeasterly. Rain chances increase later Wednesday, becoming much greater Wednesday night as deeper moisture arrives. Periods of rain are likely overnight, with lows around the lower 50s.

Thursday: A more unsettled day is expected as the approaching disturbance and frontal system cross northern Maine. Mostly cloudy skies with periods of showers are likely, and an embedded thunderstorm is possible. Temperatures should reach the mid to upper 60s, although cloud cover and precipitation could limit warming. Winds should become increasingly southwest to west before shifting northwest behind the front. Showers should diminish Thursday night as cooler and drier air arrives, with lows generally in the mid- to upper 40s.

Friday: Cooler high pressure should begin building toward northern Maine behind the departing system. Lingering clouds or an early shower cannot be ruled out, but conditions should trend drier with increasing breaks of sunshine. Highs should be held to the upper 50s to lower 60s, with a northwest breeze reinforcing the cooler air. Friday night should be mainly clear and chilly as winds diminish, with lows likely falling into the lower 40s, locally colder in sheltered valleys.

The latest Climate Prediction Center outlook favors near-normal temperatures and precipitation across northern Maine, including the Saint John Valley. Persistent troughing over Atlantic Canada should temper the warmer pattern expected farther south and west, while broad ridging remains centered over the interior United States. Early to 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: This information is based on available computer models and data and may not reflect current conditions or later forecast updates. Always visit NWS Caribou at https://www.weather.gov/car/ for the latest official watches, warnings, and advisories for northern Maine.

Credits

• Sun/Moon data from US Naval Observatory with additional information from timeanddate.com.
• NOAA Warning Banner provided by WillyWeather.com.
• Until Dec. 2026, additional Archived Weather Data from Apex Wx is at the University of Utah's MesoWest
• Apex Wx Weather Data at Synoptic Data (successor to MesoWest)
  
• Apex Wx logo by Joanna Becker ©2016 (Visit Bushi and Brush Arts Dojo)

How accurate are forecasts? On average, for the first 72 hours the accuracy is 90 percent. For days 4-7 it is 70 percent. After seven days, it is 50 percent—just good for indicating trends. On social media and other similar sites, posts that show a forecast model run a week out are just for clicks and likes, and are not considered reliable. Extended forecasts are subject to change as weather patterns evolve so should be considered guidance rather than precise predictions. Check for updated forecasts and advisories as conditions develop.