Saturday July 5, 2025

7/5/2025

Temperatures heating up with unsettled conditions
on the horizon

With a broad ridging feature remaining over the region, temperatures are expected to increase from Sunday into Monday, accompanied by moist conditions and warm temperatures, making the conditions somewhat uncomfortable. A cold front is expected to move into the region on Sunday night, bringing the chance of some storms to northern and mountainous parts of the state, with the cold front stalling over the state on Monday and into Tuesday. This slow-moving feature may bring varying rainfall amounts that could be locally heavy, and it may also increase the risk of flash flooding in areas where downpours occur. As the remnants of Tropical Storm Chantal move into the Atlantic, there is potential for some swells in the MidCoast and DownEast areas on Wednesday, which may make conditions rough on the water. A weak upper-level trough is expected to move in behind for Wednesday–Friday, bringing instability and uncertainty in terms of the movement of shortwaves around this feature.

Hot and humid conditions build on Sunday;
chance for showers and storms in the afternoon

Temperatures are expected to increase on Sunday, with moisture being advected into the region ahead of a cold front. Conditions for the day will be very warm, with high temperatures in the southern half of the state reaching the low 90s, accompanied by dew points in the 65-70 degree range. This will make for uncomfortable conditions, especially in the south, with heat indices approaching 100 degrees on the day. Conditions will be cooler along the coast with the development of a PM sea breeze. Temperatures will not be quite as hot further north, but will still be relatively warm with temperatures around 80–90 degrees. A heat advisory will be in effect from 11 AM on Sunday until 8 PM on Monday for York, southern Oxford, interior Cumberland, and Androscoggin counties. Therefore, exercise early, drink plenty of fluids, and take extra precautions if you plan to spend time outdoors.

As the cold front begins to move into the region Sunday afternoon, we’ll see a chance for some storms, primarily concentrated in the mountains and the north of the state. The first wave of storms is expected to move through north of Bangor by 1 PM, with another wave heading through in the evening. We will see considerable moisture associated with this frontal boundary, with precipitable water values above 2” across most of the region, which may produce showers and a few heavy downpours north of the mountains. The SPC currently has the northern half of the state in the Day 2 outlook at a marginal risk (potential for isolated severe storms), with the most significant threat being damaging winds and locally heavy rainfall. Daniel will have an update in the morning on Facebook.

Cold front stalls over the region Monday bringing a threat for rain north, heat and humidity continue south

Monday Midnight (05z) to Tuesday Midnight (05z) - The cold front will continue to slowly push its way towards the southeast and into more moist air on Monday, with it reaching the DownEast region by the end of the day. This will bring the chance for some showers and thunderstorms, with locally higher/lower rainfall totals throughout the region. Storms should begin moving into the region early in the day, with showers and storms continuing north of the mountains through the evening. The WPC has issued a day 3 marginal risk for excessive rainfall for the northwestern part of the state due the the risk of isolated flash flood potential. Otherwise, temperatures will still be warm in the south, with highs reaching the upper 80s, with more relief in the north with temperatures only peaking in the low 70s on the day.

A heat advisory will still be in effect until 8 PM Monday for York, southern Oxford, interior Cumberland, and Androscoggin counties, so drink plenty of fluids, and take extra precautions if you plan to spend time outdoors.

Frontal boundary sags south on Tuesday

Tuesday Midnight (05z) to Wednesday Midnight (05z) - The cold front is expected to remain stalled in the region for most of Tuesday. This likely means that there will be a few showers in the south of the state, forming inland along the coast around midday, and moving to the southeast into Tuesday night. The front should finally budge and move out of the region, helping skies to clear by Tuesday night. As a result of the cold front, temperatures on Tuesday will be much more bearable, with highs in the south only reaching the low 80s and highs in the north reaching the mid-70s.

Instability potential and uncertainty later in the week

After the passage of the cold front, a weak mid-level troughing feature is expected to become dominant over the region. This is likely to bring some instability to the area, although confidence in the amount and timing of rain is very low. Some models suggest a weak shortwave ripple in the jet stream along this trough on Wednesday, which would bring spotty showers if it materializes. However, others do not support this feature. Storms and showers are possible through the end of the week, although models disagree on how any prospective storms would play out. This upper-level trough is expected to remain over the region until midday Saturday, when another ridge is expected to move in, helping temperatures warm up and skies to break up.

Temperature outlook through Friday

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Today's update prepared by Michigan State student intern Harry Fuess

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