Apex Wx

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Wednesday, September 16 – Friday, September 18

Overview: A weak surface trough crossing northern Maine today may bring an isolated shower, but most of the Saint John Valley will remain dry and mild with temperatures running above normal. Partial clearing tonight, light winds, and lingering low-level moisture will favor patchy river-valley fog toward Thursday morning.

Thursday will be a transition day as low pressure moves east across Quebec and an associated cold front approaches northern Maine. Clouds will increase, but current guidance keeps the deeper moisture and steadier rainfall mainly south of the Saint John Valley. The front and upper-level trough cross Friday, bringing a few light showers and a much more noticeable change to cooler, windy weather. Strong cold-air flow and daytime mixing will allow northwest winds to gust around 30–40 mph Friday, making wind rather than rainfall the primary concern with this system.

Wednesday: A few isolated showers are possible early this morning, but most of the day will be dry across Fort Kent, Madawaska, Frenchville, St. Agatha, Van Buren, and the surrounding Saint John Valley. Skies should become partly sunny, with temperatures reaching the lower 70s, around 5–10°F above mid-September normals. South winds around 5–10 mph will turn west during the afternoon, with gusts occasionally near 20 mph. Tonight will be partly cloudy and considerably cooler, with lows in the lower 40s. Patchy valley fog should develop after midnight.

Thursday: Any early valley fog should dissipate by around 8 AM, followed by a partly sunny and seasonably cool day. Highs will reach the mid-60s, with light and variable winds. Clouds will increase Thursday night as the Quebec low and associated cold front approach. Despite the approaching system, current guidance favors the Saint John Valley remaining largely dry, with the better chance for steadier rain well to the south. Thursday night will be mostly cloudy with lows in the mid-40s and light winds.

Friday: The cold front and upper trough will cross northern Maine, bringing a chance of showers mainly from mid-morning into early afternoon. Rainfall should be light, generally less than 0.10 inch around Fort Kent, with a 50% chance of precipitation. Temperatures will struggle to reach the upper 50s to around 60°F, several degrees below normal. The more important feature will be rapidly increasing northwest winds: 15–20 mph with gusts around 30–35 mph, locally approaching 40 mph. Isolated tree damage or power interruptions are possible. Showers diminish during the afternoon, followed by mostly clear skies Friday night. Northwest winds remain gusty into the evening before gradually easing, with lows falling into the mid- to upper 30s.

Saturday, September 19 – Tuesday, September 22

Overview:  Cooler, drier air arriving behind Friday’s cold front will settle across the Valley for the start of the weekend. High pressure building into northern New England should bring a sunny but cool Saturday, with temperatures remaining around 60°F after a chilly start.

The high will begin shifting east Saturday night as another disturbance approaches Sunday. Clouds will increase, with scattered showers possible mainly from late morning into the afternoon, although current guidance suggests substantial dry periods and remains uncertain about the system’s exact track and timing.

Monday currently looks mainly dry as weak high pressure returns. Another minor disturbance may bring a slight chance of showers Monday night into Tuesday, but much of Tuesday should remain dry. Clearing Tuesday night will allow temperatures to fall into the upper 30s.

Saturday: High pressure building behind Friday’s front should provide a dry, bright, and cool day across the Fort Kent area and the surrounding Saint John Valley. Mostly sunny skies are expected, with highs only in the upper 50s to around 60°F, several degrees below normal. Northwest winds will be considerably lighter than Friday but may remain somewhat noticeable early. Saturday night becomes partly cloudy, with lows in the upper 30s.

Sunday: The next disturbance approaches as high pressure shifts east. Clouds should increase, with showers becoming possible mainly from late morning into the afternoon. Current NWS guidance carries only a 30% chance of precipitation, so substantial dry periods remain possible. Highs should reach the lower 60s. The exact timing and coverage of showers remain uncertain because guidance has not settled on the track of the approaching system. Sunday night currently trends partly cloudy and cool, with lows in the upper 30s to around 40°F.

Monday: Currently, a mainly dry day is expected behind the Sunday disturbance, with mostly sunny skies and highs near the lower 60s. The lack of a stronger temperature response suggests that the air mass will remain seasonably cool rather than turn sharply colder. Clouds may increase again Monday night, with a 20% chance of showers and lows around 40°F.

Tuesday: Another weak disturbance or frontal feature may pass close enough to maintain a slight chance of showers, but the day currently appears predominantly dry with at least some sunshine. Temperatures should reach the lower to mid-60s. Tuesday night will become mostly clear, with temperatures falling into the upper 30s, around 37°F. With clearing skies and light winds, sheltered portions of the Saint John Valley may again need to be watched for localized frost potential.

Long Range: Wednesday, September 23 – Tuesday, September 29

Normal temperatures across the Saint John Valley during this period are generally around 60°F for daytime highs and upper 30s to lower 40s for overnight lows, with temperatures continuing their seasonal decline. CPC outlooks favor above-normal temperatures and below-normal precipitation across northern Maine. Broad ridging across eastern North America and a tendency toward surface high pressure favor a generally warmer and drier pattern for the period.

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.
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• 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.

How accurate are forecasts?

Forecast confidence generally decreases as lead time increases. Forecasts for the next few days usually provide considerably more detail and confidence than forecasts a week or more in advance. Beyond about 7 days, forecasts are most useful for identifying broader weather patterns and temperature or precipitation trends rather than predicting exact conditions at a particular place and time.

Individual computer-model runs—especially those depicting specific storms, snowfall amounts, or other details a week or more in advance—should not be treated as forecasts by themselves. Extended forecasts will change as new observations become available and models better resolve the evolving atmospheric pattern. Check updated forecasts as the event approaches.

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