SOUTHERN VERMONT — A thick veil of wildfire smoke high in the atmosphere is transforming the sky over our local Bennington and Windham Counties this week – casting an eerie glow, muting the sun, and leaving air quality in the moderate range – even as temperatures and humidity remain oppressive.
According to federal forecasters, the hazy and particulate-laden sky and unusual colors are the result of smoke from more than 830 active wildfires burning across Canada and northern Minnesota, funneled into New England by the jet stream and trapped over the region by stubborn weather patterns.
What people are seeing, and why the sky looks so strange
Over the course of Wednesday, residents across Southern Vermont reported the sky shifting from orangey‑yellow to umber to violet hues tinged with pink, with a yellow cast over the landscape and a deep red or dark orange sun, especially nearest to sunrise and sunset.
On a normal and clear day in Southern Vermont, tiny molecules in the atmosphere scatter mostly blue light, which is why the sky appears blue.
However, this week, the air is filled with larger particulate matter from wildfire smoke, which scatters longer wavelengths of light – oranges and reds – in a process known as Mie scattering (pronounced “mee,” and named after physicist Gustav Mie who first published the mathematical description of this weird-looking light-scattering phenomenon).
Due to Mie scattering, the sky can appear milky white, with sepia tones, or faintly pink‑violet, instead of blue. The sun may appear like a dark orange or red disk, especially when low to the horizon, and sunlight at ground level feels weaker and more filtered, as if being viewed through rose-tinted glasses. And these are the effects that we are currently experiencing.
Where the smoke is coming from, and how it travels
Federal agencies have reported that more than 800 wildfires are burning in Canada, with additional fires in northern Minnesota near the Canadian border. Many of these are large, and burning through dense boreal forests with little or no containment.
These blazes have triggered evacuations at their locales and in the surrounding areas, and are attributed to areas experiencing intensive drought.
The smoke created from these wildfires reaches Vermont through a series of atmospheric steps.
The jet stream’s “conveyor belt” of high‑altitude winds scoop up smoke from the Central Canada region and carry it southeast across the Great Lakes and into New England.
A high‑pressure “lid” forms, where a strong high‑pressure system causes air to sink (a process known as subsidence) which then presses some of the elevated smoke closer to the surface.
A stalled weather pattern can occur, where slow‑moving systems over Canada and the Northeast keep the flow of smoke aimed at the region instead of sweeping it quickly away.
These patterns mean that – even though the fires are hundreds of miles away – fine particulate matter (PM2.5) from those blazes is now suspended over Vermont and neighboring states.
Local air quality: Moderate, with cautions for sensitive groups
On Wednesday, air quality in Bennington and Windham Counties sat in the “moderate” category, with the Air Quality Index (AQI) fluctuating roughly between the low‑50s and high‑90s. This was driven primarily by PM2.5 from the presence of wildfire smoke.
In practical terms, most healthy adults can go about their normal routines outdoors. However, more sensitive groups – older adults, children, people with asthma, COPD, or heart disease – are advised to limit prolonged or heavy exertion outside, especially during the haziest periods.
Those with prolonged exposure may notice throat irritation, mild coughing, or even eye discomfort – particularly during intense exercise.
Residents can track real‑time conditions using the federal AirNow “Fire and Smoke Map” and Vermont‑specific dashboards, which show localized AQI readings as plumes shift during the day on Thursday.
How the smoke is affecting storms, heat, and humidity
The same smoke that is changing the sky’s color is also subtly reshaping the weather over Southern Vermont.
Forecasters note several key effects. These include solar dimming, where smoke particles in the upper atmosphere scatter and absorb sunlight, acting as a partial sunblock. This can shave a few degrees off daytime highs, compared with what might otherwise occur under clear skies.
It can also include “capping inversion.” By warming the air aloft, the smoke can create a “cap” – a warm layer that suppresses rising air. This can weaken thunderstorms, even when surface heat and humidity are high.
Another key effect is cloud microphysics, where extra smoke particles provide millions of tiny surfaces for water vapor to cling to, producing many “very tiny” droplets rather than fewer larger raindrops. These smaller droplets don’t fall as easily, which can reduce heavy rainfall and the actual structure of a storm.
For example, on Tuesday night, Southern Vermont sat under extremely high humidity fueled by warm southerly winds pulling tropical moisture up the East Coast ahead of a cold front. Under normal conditions, that setup could have produced stronger thunderstorms. Instead, wildfire smoke likely muted the intensity of those expected storms, leaving the region with more of a muggy “soupy” feeling than the explosive severe weather that many expected.
Short‑term outlook for southern Vermont
Through Wednesday and into Thursday, forecasters expect the following for our Southern Vermont region:
- Sky conditions – Persistent haze and milky skies, with periods of thicker smoke as the plumes shift southward and then rise again. The sun may remain reddish or orange at times.
- Temperatures and humidity – Highs in the mid‑80s, with oppressive humidity at times, especially ahead of the next cold front.
- Air quality – AQI values are forecast to remain in the moderate range, occasionally bordering on “unhealthy for sensitive groups” during heavier smoke intrusions (these are expected through Thursday).
- Showers and storms – As another cold front approaches us on Thursday, scattered showers are expected with isolated downpours and localized “non‑severe” thunderstorms. (Smoke may again limit storm strength somewhat.)
By Friday, higher pressure and drier air are expected to build in from the west, bringing more seasonable temperatures in the upper 70s to mid‑80s, lower humidity, and improved air quality – though some high‑level haze may linger.
For now, we will continue to look at our landscape through our “rose-colored” glasses.
