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Could Montreal's Clouds Have Created the UFO?

Low cloud, reflected urban lighting and optical diffusion could produce stationary-looking luminous patches without a large object overhead.

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On this page

  • Weather and cloud conditions during the sighting
  • How urban light can spread through low cloud
  • Which witness details the cloud explanation fits or fails
Preview for Could Montreal's Clouds Have Created the UFO?

Introduction

One of the most frequently proposed conventional explanations for the 7 November 1990 Hotel Bonaventure sighting is that observers were not looking at a gigantic solid object at all, but at bright urban lights illuminating a low cloud layer. This “cloud theory” matters because the surviving photographs show diffuse light rather than a sharply defined structure, and many witnesses described glowing patches or lights whose edges seemed to merge into the cloud. At the same time, the explanation is not a complete solution. Some details reported by witnesses appear compatible with illumination within cloud, while others remain difficult to reconcile with a simple reflection from a single light source. The result is a case in which meteorology and urban lighting provide a plausible mechanism, but one that still has important unanswered questions.[Wikipedia]WikipediaOvni au dessus de Montréal en 1990Ovni au dessus de Montréal en 1990

Cloud Theory illustration 1

Could Montreal’s Clouds Have Created the UFO?

The cloud explanation begins with a straightforward physical principle. A low, continuous cloud deck acts as a reflective and scattering surface. Powerful lights from the ground do not always produce a recognisable beam. Instead, moisture droplets inside the cloud scatter the light in many directions, creating broad luminous patches that can appear suspended overhead.

In a dense city such as central Montreal, numerous light sources contribute to this effect. Construction floodlights, illuminated office buildings, advertising displays and street lighting can combine to brighten portions of low cloud. Under the right conditions, several separate sources may merge into a pattern that appears larger and more coherent than any individual lamp.

This mechanism is well known to meteorologists and astronomers. Low cloud often makes urban “skyglow” dramatically brighter than clear skies because the cloud reflects artificial light back towards observers rather than allowing it to escape into space. The effect can make bright patches appear almost stationary even though there is no physical object at the illuminated location.[Wikipedia]WikipediaOvni au dessus de Montréal en 1990Ovni au dessus de Montréal en 1990

Multiple witnesses saw huge UFO hovering above the Bonaventure hotel, Montréal, Canada, Nov. 7, 1990

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Weather and cloud conditions during the sighting

Weather conditions reported for the evening are broadly compatible with strong light diffusion. Contemporary investigations describe an extensive low cloud layer over Montreal, with cloud height changing during the observation period. Such conditions are exactly those in which artificial lighting can create diffuse glowing regions rather than distinct points of light.[Wikipedia]WikipediaOvni au dessus de Montréal en 1990Ovni au dessus de Montréal en 1990

The photographs taken during the event also support the presence of substantial cloud. Instead of revealing a sharply bounded craft, they show an irregular bright area embedded within cloud, with soft edges that blend into the surrounding sky. This appearance is consistent with illumination inside or beneath cloud, although it cannot by itself identify the original light source.

The Montreal UFO of 1990 - Montreal, Quebec, Canada

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How urban light can spread through low cloud

Several mechanisms have been suggested.

  • Construction lighting. At the time, major construction projects in downtown Montreal used powerful floodlights capable of illuminating cranes and upper floors. These lights were an obvious early suspect because they pointed upwards and operated close to the observation site.[TVA Nouvelles]tvanouvelles.caOpen source on tvanouvelles.ca.
  • Combined city illumination. Rather than a single spotlight, multiple urban light sources may have blended within the cloud deck to produce a broad luminous pattern without any obvious origin.
  • Optical diffusion. Water droplets inside cloud scatter light repeatedly, enlarging bright areas and blurring their boundaries. This can make separate lights appear connected into one larger glowing form.
  • Changing cloud thickness. As cloud density varies, illuminated patches may brighten, fade or appear to shift shape without the light sources themselves moving.

These mechanisms explain why witnesses might perceive an apparently enormous luminous area even when no large physical object occupied that space.

Cloud Theory illustration 2

Which witness details the cloud explanation fits or fails

The cloud hypothesis matches several important aspects of the reports.

It explains why many witnesses described indistinct outlines rather than clear structural features. If observers were viewing illuminated cloud rather than a solid craft, different people could naturally interpret the same glowing regions as an oval, a ring of lights or simply bright patches in the sky. It also fits the photographs, which record diffuse illumination rather than sharp edges.[Wikipedia]WikipediaOvni au dessus de Montréal en 1990Ovni au dessus de Montréal en 1990

The theory is also consistent with disagreements over the object’s exact shape and position. Human depth perception is poor at night when there are few visual reference points. A bright area within cloud can seem fixed overhead from one position while appearing slightly displaced from another.

However, the explanation has notable weaknesses.

The strongest objection concerns reports that police arranged for floodlights on a nearby construction site to be switched off without any obvious change in the appearance of the phenomenon. If those particular lights had been responsible, the display should have altered noticeably. Investigators who argued for an unidentified object regarded this as important evidence against a simple construction-light explanation.[ufoforum.it]ufoforum.itit • Leggi argomento• Leggi argomento - L'UFO di Montreal (7 Novembre 1990)…

Another difficulty is the reported duration. The lights remained visible for several hours while witnesses described gradual changes rather than rapid fluctuations. A cloud-based explanation therefore requires either a stable combination of multiple urban light sources or another persistent source of illumination, not merely a single beam briefly striking the cloud deck.

Some later commentators have argued that critics focused too narrowly on one construction site. Even if one set of floodlights was eliminated, the wider downtown core contained many other intense light sources capable of contributing to the overall glow. This possibility keeps the cloud hypothesis viable, although it remains difficult to reconstruct the precise lighting environment more than three decades later.[Wikipedia]WikipediaOvni au dessus de Montréal en 1990Ovni au dessus de Montréal en 1990

The Proof Is Out There: Bizarre UFOs Hover Over Montreal (Season 3) | History

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Why the cloud explanation remains plausible but unproven

The cloud-and-city-lights explanation occupies an important middle ground in assessments of the Hotel Bonaventure case. It accounts for several of the strongest physical observations: diffuse photographs, uncertain outlines, inconsistent witness estimates of shape and the known presence of low cloud over central Montreal. These are exactly the conditions in which atmospheric optics can produce striking visual displays.

At the same time, the theory has never identified a single confirmed light source that reproduces every reported feature of the event. The unsuccessful attempt to test one nearby construction lighting system, together with the prolonged visibility of the display, means the conventional explanation cannot be regarded as conclusively demonstrated.

For that reason, the Hotel Bonaventure incident is best understood not as a straightforward debunking or a confirmed extraordinary craft, but as a well-documented case in which ordinary atmospheric optics offer a credible mechanism that explains much of the evidence while leaving some observational details open to debate.[wikipedia.org]WikipediaOvni au dessus de Montréal en 1990Ovni au dessus de Montréal en 1990

Cloud Theory illustration 3

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Endnotes

1. Source: Wikipedia
Title: Ovni au dessus de Montréal en 1990
Link:https://fr.wikipedia.org/wiki/Ovni_au-dessus_de_Montr%C3%A9al_en_1990

2. Source: ufoforum.it
Title: it • Leggi argomento
Link:https://www.ufoforum.it/viewtopic.php?f=3&start=0&t=7779

Source snippet

• Leggi argomento - L'UFO di Montreal (7 Novembre 1990)...

3. Source: ised-isde.canada.ca
Link:https://ised-isde.canada.ca/site/science/en/office-chief-science-advisor/sky-canada-project/management-public-reporting-unidentified-aerial-phenomena-canada

Source snippet

of Public Reporting of Unidentified Aerial Phenomena in CanadaJune 1, 2025 — UAP sightings in the media and the public Public sightings o...

Published: June 1, 2025

4. Source: tvanouvelles.ca
Link:https://www.tvanouvelles.ca/2020/11/06/il-y-a-30-ans-lovni-de-la-place-bonaventure-fascinait-les-montrealais

Additional References

5. Source: facebook.com
Title: 1990ufo phenomenon over montrealon nov 7 1990 a woman spots something in the sky
Link:https://www.facebook.com/100064620102910/posts/1990ufo-phenomenon-over-montrealon-nov-7-1990-a-woman-spots-something-in-the-sky/719651640198833/

Source snippet

Montreal Golden Oldies | FacebookNovember 8, 2023 — MONTREAL GOLDEN OLDIES'S POST * * * MONTREAL GOLDEN OLDIES November 8, 2023 1990: UFO...

Published: November 8, 2023

6. Source: journaldemontreal.com
Title: Le Canada aura son bureau des ovnis | Le Journal de Montréal
Link:https://www.journaldemontreal.com/2025/07/16/le-canada-aura-son-bureau-des-ovnis

Source snippet

July 16, 2025 — LE CANADA AURA SON BUREAU DES OVNIS OTTAWA VEUT RASSEMBLER LES TÉMOIGNAGES LIÉS AUX PHÉNOMÈNES AÉRIENS NON IDENTIFIÉS Ima...

Published: July 16, 2025

7. Source: toronto.citynews.ca
Title: some of the best known canadian ufo sightings over the years
Link:https://toronto.citynews.ca/2025/07/18/some-of-the-best-known-canadian-ufo-sightings-over-the-years/

Source snippet

of the best-known Canadian UFO sightings over the yearsJuly 18, 2025 — SOME OF THE BEST-KNOWN CANADIAN UFO SIGHTINGS OVER THE YEARS Image...

Published: July 18, 2025

8. Source: sidequestsofreality.com
Title: Episode SQR-UFO-008: The Place Bonaventure Incident
Link:https://www.sidequestsofreality.com/p/episode-sqr-ufo-008-the-place-bonaventure

Source snippet

May 7, 2026 — SIDE QUESTS OF REALITY Side Quests of Reality Episode SQR-UFO-008: The Place Bonaventure Incident 1× 0:00 Current time: 0...

Published: May 7, 2026

9. Source: youtube.com
Link:https://www.youtube.com/watch?v=hTHeoPigkFU

Source snippet

Montreal UFO 1990 lights hotel bonaventure Montreal 1990 Mass UFO Sighting Missing Information...

10. Source: youtube.com
Title: The Proof Is Out There: Bizarre UFOs Hover Over Montreal (Season 3)
Link:https://www.youtube.com/watch?v=9ncD9oMSmAs

Source snippet

Multiple witnesses saw huge UFO hovering above the Bonaventure hotel, Montréal, Canada, Nov. 7, 1990...

11. Source: youtube.com
Link:https://www.youtube.com/watch?v=IyhHQ0d6RJk

Source snippet

The Proof Is Out There: Bizarre UFOs Hover Over Montreal (Season 3)...

12. Source: ovnis-direct.com
Title: ovni de montreal novembre 1990
Link:https://ovnis-direct.com/ovni-de-montreal-novembre-1990/

Source snippet

Ovni de Montréal Novembre 1990 - OVNIS-DIRECT...

13. Source: signalementsovni.com
Link:https://signalementsovni.com/vaisseau-spatial-observe-au-dessus-de-lhotel-bonaventure-a-montreal-7-novembre-1990/

14. Source: qub.ca
Title: Il y a 30 ans, un OVNI dans le ciel du centre-ville de Montréal | 24heures
Link:https://www.qub.ca/article/il-y-a-30-ans-un-ovni-dans-le-ciel-du-centre-ville-de-montreal-1094734994