Apex Wx

Overview:  Following Tuesday’s cool and cloudy conditions, the Valley will turn warmer and drier Wednesday and Thursday as high pressure becomes the dominant influence. Lingering low-level moisture will support areas of dense river-valley fog early Wednesday, with locally poor visibility before daytime warming and mixing allow the fog to dissipate. Dry conditions should then prevail through Wednesday night, although patchy fog may redevelop in sheltered valleys overnight.

Thursday will bring the most noticeable change as southwest flow strengthens between departing high pressure and low pressure moving across Canada. Warmer air will spread into northern Maine, allowing temperatures to climb well above those earlier in the week. Southwest winds will also become increasingly breezy during the afternoon, with gusts potentially reaching 20–25 mph.

Conditions change Thursday night into Friday as a cold front approaches from the northwest. Clouds will increase first, followed by showers spreading into northern Maine. Some uncertainty remains concerning the exact timing of the front, but showers are expected at times Friday before diminishing Friday evening. Rainfall should generally remain modest. Behind the front, winds will shift and cooler, drier air will begin returning to the Saint John Valley for the weekend.

Wednesday: Areas of dense fog early, followed by improving visibility and a mostly cloudy but dry day. Temperatures should reach around 70°F, with light and variable winds. Mostly cloudy Wednesday evening, then gradually becoming mostly clear overnight. Patchy valley fog may redevelop, with lows in the upper 40s.

Thursday: Partly sunny, warmer, and increasingly breezy. Temperatures rise into the middle 70s, with southwest winds strengthening during the day and gusts potentially reaching around 25 mph. Clouds increase Thursday night, with a slight chance of showers developing after evening and lows in the middle 50s.

Friday: A cold front crossing northern Maine will bring a chance of showers, with the timing still somewhat uncertain. Current guidance favors the better shower opportunity later in the day, although precipitation may arrive earlier depending on frontal progression. Temperatures should reach the mid- to upper 60s before cooler air begins filtering into the region. Showers remain possible Friday evening before diminishing, with lows falling into the lower 40s.

Saturday, October 3 – Tuesday, October 6

Overview: Following Friday’s cold frontal passage, cooler and drier Canadian air will settle across northern Maine for the weekend. High pressure building behind the front will provide a dry Saturday, although northwest winds may remain somewhat breezy during the day. As the high moves closer Saturday night, winds will diminish and skies remain mostly clear, creating favorable conditions for strong nighttime cooling. Temperatures may approach freezing across the Valley, with colder readings and frost possible in sheltered locations.

Sunday begins dry under the lingering influence of high pressure, but clouds will gradually increase as the next disturbance approaches from the west. A progressive northern-stream pattern will bring another frontal system across the County Sunday night into Monday, producing a period of showers. Rainfall should remain relatively modest, with the better opportunity for precipitation occurring Sunday night and continuing at times Monday.

The system will move east Monday night, allowing showers to diminish as another push of cooler and drier Canadian air arrives. Tuesday should turn drier and noticeably cooler, with high pressure beginning to regain influence. Overall, the period features two cool early-October air masses separated by a relatively brief period of clouds and showers Sunday night into Monday.

Saturday: Sunny, dry, and seasonably cool, with highs in the upper 50s. Northwest winds may remain somewhat breezy during the day. Mostly clear Saturday night with excellent radiational cooling; lows should fall into the lower 30s, with colder readings possible in sheltered locations. Frost or a freeze will be possible.

Sunday: Partly sunny and cool with highs in the upper 50s to near 60°F. Clouds should gradually increase as the next disturbance approaches. Showers become increasingly likely Sunday night, with mostly cloudy skies and lows in the upper 30s. Current NWS guidance places the nighttime rain chance near 60 percent.

Monday: Partly sunny with a chance of showers, particularly as the disturbance and frontal boundary cross northern Maine. Highs should reach the middle 50s. Showers remain possible Monday evening before becoming less numerous overnight. Mostly cloudy and colder Monday night with lows in the lower 30s.

Tuesday: A cooler and drier day is expected behind the departing system. Skies should become mostly sunny, but renewed Canadian air will hold afternoon temperatures in the lower 50s. Dry conditions are expected Tuesday night, with overnight lows falling into the lower 30s under partly cloudy skies.

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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