Apex Wx

via Google Translate

Saturday, September 12 – Monday, September 14

Overview: High pressure crossing northern New England will provide a quiet start to the weekend after this morning’s cold conditions. A Frost Advisory remains in effect through 8 AM, with patchy frost and fog possible in colder locations before quickly dissipating. Mostly sunny skies, dry air, and southwest winds around 5–10 mph will then allow temperatures to rebound sharply into the lower 70s. The high shifts east tonight, with strengthening southerly flow bringing increasing clouds and considerably milder temperatures.

Sunday becomes increasingly unsettled as a cold front approaches from Canada and deeper moisture spreads into northern Maine. Showers become more numerous during the afternoon and widespread Sunday night, with an isolated thunderstorm possible. Atmospheric moisture will be unusually high for northern Maine, so stronger showers or thunderstorms may produce locally heavy rainfall and some roadway ponding, although significant flooding is not expected. The front crosses Sunday night into Monday morning, followed by cooler and drier northwest flow. Rain gradually ends Monday, with clearing and another chilly night expected as high pressure returns.

Saturday: Patchy frost and valley fog around sunrise give way to mostly sunny skies and a very pleasant day. Temperatures rebound into the lower to mid-70s, with southwest winds around 5–10 mph. Clouds increase Saturday night as southerly flow develops ahead of the approaching front. Lows remain considerably milder in the lower 50s, with south winds around 5–10 mph.

Sunday: Clouds thicken as the cold front approaches northern Maine, with showers becoming increasingly likely during the afternoon and an isolated thunderstorm possible. Highs reach the upper 60s to around 70°F, with south winds increasing to 5–10 mph and becoming gusty. Rain becomes widespread Sunday night, potentially moderate at times, with an isolated thunderstorm remaining possible. Southerly winds may also remain gusty before turning northwest behind the front. Lows settle into the upper 40s to lower 50s.

Monday: Showers remain likely during the morning before gradually ending as the front moves east. Clouds give way to increasing breaks of sunshine as cooler and drier west to northwest flow spreads across the Valley. Highs reach the upper 50s to lower 60s, with northwest winds remaining around 10–15 mph during the afternoon. Monday night turns clear as high pressure moves closer and winds diminish, allowing temperatures to fall into the upper 30s to around 40°F.

Tuesday, September 15 – Friday, September 18

Overview: Following Monday’s cooler post-frontal weather, high pressure will provide a mainly dry and seasonably cool Tuesday across Fort Kent and the Saint John Valley. A mixture of sunshine and clouds is expected, with relatively light winds and temperatures recovering into the mid-60s. The high shifts east later Tuesday, allowing southerly flow to develop ahead of the next cold front. Clouds increase Tuesday night, with temperatures remaining considerably milder than Monday night.

Wednesday becomes warmer as southerly flow draws milder air northward, with highs potentially reaching the lower 70s despite considerable cloud cover. Passing showers are possible as the front approaches, but rainfall should be intermittent rather than continuous. The boundary crosses northern Maine Wednesday night into Thursday, bringing additional clouds and a few showers before cooler west to northwest flow returns. Moisture appears limited, so no significant rain event is expected. High pressure then begins building back toward northern Maine Thursday night into Friday, favoring increasing dry periods, some returning sunshine, and seasonably cool temperatures to end the workweek.

Tuesday: High pressure provides a mainly dry and seasonably cool day with a mixture of sunshine and clouds. Highs reach the mid-60s, with relatively light winds gradually becoming southerly. Clouds increase Tuesday night ahead of the next frontal system, with lows in the upper 40s to around 50°F.

Wednesday: Mostly cloudy skies and a few passing showers are possible as the system approaches northern Maine. Southerly flow brings a noticeable temperature rebound, with highs reaching the upper 60s to lower 70s. Showers remain possible Wednesday night as the front moves closer or begins crossing the region, with lows in the upper 40s to around 50°F.

Thursday: A cooler and mostly cloudy day follows as the front moves through. A few rain showers remain possible, particularly during the afternoon, with highs in the lower to mid-60s. Winds gradually turn west to northwest behind the boundary. Thursday night trends partly to mostly cloudy and cooler as shower chances diminish, with lows in the lower to mid-40s.

Friday: High pressure begins building toward northern Maine from the Great Lakes region, bringing a mainly dry and seasonably cool end to the workweek. Clouds give way to some breaks of sunshine, with highs in the lower to mid-60s. West to northwest winds remain relatively light. Friday night looks partly cloudy and chilly, with temperatures falling to around 40°F to the lower 40s.

Long Range: Saturday, September 19 – Friday, September 25

The latest outlook favors below-normal temperatures and below-normal precipitation across the Valley for the period. A developing trough over eastern North America should support a cooler pattern across the Northeast, with an increased chance of an early-season cold spell late in the period. Late-September climatology across the Valley generally features daytime highs in the lower to mid-60s and overnight lows in the upper 30s to lower 40s.

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.

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.

Weather Apps

Most weather apps rely heavily on automated forecast data. They can be useful for a quick look at routine weather, but automated forecasts may miss important local details or the significance of rapidly changing conditions. During hazardous or changing weather, consult weather.gov and other official National Weather Service information rather than relying solely on an app.

Radar Apps

Weather radar is an invaluable tool for tracking precipitation and storms, but radar images should not be interpreted as a real-time picture of conditions at the ground. Data collection, processing, transmission, mosaicking, and app updates can introduce delays, and radar detects energy returned from precipitation at varying heights above the surface. During rapidly developing or moving storms, conditions at your location may therefore differ from what a radar app appears to show. Use radar together with current observations and official National Weather Service warnings.