Apex Wx

Fort Kent & the Saint John Valley, Maine
Weather Information

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A strong upper-level trough and associated surface low moving through Quebec will drive a cold front across northern Maine on Friday. Strengthening southwesterly flow ahead of the front will bring increasingly moist air into the Saint John Valley. Patchy morning fog will give way to widespread showers, with thunderstorms becoming possible during the day and continuing into the evening. Highs will reach the low to mid 70s, with southwest winds around 5–10 mph. Some thunderstorms could produce gusty winds, small hail, and locally heavy rainfall, although the extent of stronger storms will depend on daytime heating and the timing of the front. Showers and thunderstorms will diminish Friday night as the front moves east, with lows falling to around 50 overnight.

Cooler and drier air will arrive Saturday behind the front as west to northwest flow develops. Despite lingering colder air aloft, increasing high pressure and subsidence should provide mostly sunny to sunny skies. Highs will reach the low 70s. Mostly clear skies and diminishing winds Saturday night will favor efficient cooling, particularly in sheltered portions of the Saint John and Fish River valleys, with lows in the upper 40s.

Weak high pressure should maintain mainly dry and mostly sunny weather Sunday, with temperatures recovering into the low to mid-70s. Clouds will increase Sunday night as another disturbance approaches within the broader upper-level trough over eastern Canada. Scattered showers and thunderstorms may develop, with overnight temperatures falling into the low 50s.

Forecast confidence decreases somewhat by Monday because of uncertainty regarding the timing and strength of the approaching disturbance. A few showers remain possible, but considerable dry weather and periods of sunshine are expected. Temperatures will reach the low 70s. Any lingering showers should gradually diminish Monday night, followed by partly cloudy skies and lows around 50.
Climate Prediction Center outlooks favor near-normal temperatures and above-normal precipitation across the Saint John Valley. The upper-level pattern should become less amplified, although periodic troughs and frontal passages will maintain a changeable pattern with opportunities for showers followed by brief periods of cooler Canadian air. Considerable uncertainty remains regarding the timing and strength of individual systems. Early-September normals around Fort Kent feature daytime highs near 70 and overnight lows in the upper 40s, gradually cooling through the period. At present, seasonable temperatures with periodic unsettled weather are favored over persistent warmth or an extended cool spell.