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Striking Contrast: Plains reel under dense fog, but sunny-side up in Himachal hilly regions — scientists explain why

Meteorological experts attribute this sharp contrast between the plains and the hills to a combination of topography, wind patterns, moisture levels and pollution load.

4 min readShimlaJan 14, 2026 08:55 PM IST

Clear sky and bright sunshine in Sanjauli, Shimla, on Wednesday. (Express photo)

At a time when people in neighbouring states like Punjab and Haryana and the Union Territory of Chandigarh are battling poor visibility and severe cold conditions caused by dense to very fog, hilly regions of Himachal Pradesh bear a strikingly different weather pattern, marked by bright sunshine and clear skies.

Meteorological experts attribute this sharp contrast between the plains and the hills to a combination of topography, wind patterns, moisture levels and pollution load.

According to experts, stagnant air and moisture accumulation make the plains prone to fog formation, whereas the downward flow of winds from higher elevations to lower, the absence of large waterbodies, and relatively low levels of pollutants in the hill regions are the primary reasons behind the clearer conditions in Himachal’s higher reaches.

However, not all areas of Himachal are spared. Several low-lying regions in the state, like Una, Bilaspur, Kangra, Nalagarh, Baddi (Solan district) and Paonta Sahib (Sirmaur district), among others, are vulnerable to dense fog, low visibility and intense cold — much like the adjoining plains.

Traffic moves smoothly on a bright sunny day at Kandaghat in Solan district on Wednesday. (Expres photo)

Una recorded dense fog with 50m visibility, while Paonta Sahib recorded shallow fog with a 500m visibility on Wednesday morning.

Explaining the phenomenon, scientist Sandeep Kumar Sharma of the India Meteorological Department (IMD), Shimla, said the contrast between the plains and hill regions became particularly evident in recent days.

“The hills of Himachal Pradesh, including Shimla, Kasauli, Chail and Dharamshala, are experiencing bright sunshine and clear skies. There are three main reasons behind this,” Sharma said. “First, winds flow from higher elevations to lower. Second, these winds are weak and largely motionless, so they descend easily towards the plains, but lose momentum there, leading to a drop in temperature. Third, the presence of rivers, streams, waterbodies and higher pollutant content in the plains increases moisture, which aids fog formation.”

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Sharma said fog-prone conditions are not limited to plains alone. “Similar situations also develop in valleys — low-lying areas between hills or mountains — even in mountainous states like Himachal Pradesh,” he said.

Offering further insight, scientist Surinder Paul, in-charge of the IMD Chandigarh, told The Indian Express, “Weak northerly winds play a crucial role in fog formation. The northerly wind, which blows from north to south, is weak. When it reaches the plains and valleys and comes into contact with moisture, fog forms. The presence of pollutants further increases the density of fog.”

Paul explained that during winter, plains frequently experience temperature inversion, a phenomenon in which colder air becomes trapped near the ground while warmer air remains above it. “This inversion restricts vertical air movement, allowing moisture, pollutants and cold air to accumulate near the surface, leading to persistent fog and smog,” he said.

Drawing a comparison with monsoon conditions, Paul, who previously served as an IMD in-charge in Shimla, said hills do experience fog-like conditions during the monsoon, but these are actually low clouds. “These clouds typically form at a height of around two kilometres and fall under the category of low clouds,” he said.

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“In winter, hill stations remain above the inversion layer. At higher elevations, the air is relatively warmer and drier, allowing sunlight to pass through easily,” he added.

While western disturbances may occasionally bring cloud cover or snowfall to higher reaches, meteorologists say in their absence, hill regions often enjoy crisp, sunny days, even as the plains below remain shrouded in fog for prolonged periods.

Saurabh Parashar

Saurabh Parashar is an Assistant Editor at The Indian Express, primarily responsible for the publication’s coverage of Himachal Pradesh. He is a seasoned journalist with over 17 years of experience in print media, specializing in crime, legal affairs, and investigative reporting. Professional Background Education: He holds a Master’s degree in Mass Communication from Guru Jambheshwar University of Science & Technology (Hisar) and a Law degree from Himachal Pradesh University (HPU), Shimla. This legal background significantly informs his reporting on complex judicial and administrative matters. Career Path: Before joining The Indian Express in 2017, he spent 12 years with The Times of India. Core Beats: His primary focus is the socio-political landscape of the hill state, with a specific emphasis on the environment, forest conservation, drug menace (specifically "Chitta"), affairs related to tribal and archaeology and the unique challenges of governance in high-altitude regions. Recent Notable Articles (Late 2025) His recent reporting highlights the critical intersection of policy, law, and social safety in Himachal Pradesh: 1. "Himachal’s battle against Chitta: Why the border areas are most vulnerable" (Late 2025): An investigative look at the transit routes from Punjab and the impact on local youth. 2. "Shimla ropeway clears key hurdle as 820 trees face the axe :According to the Forest Survey of India’s 2021 assessment, 47.21 percent of Shimla’s 5,131 sq km geographical area is under forest cover (Nov 17, 2025). 3. "Himachal to handover 2.7427 ha of non-forest land for Shimla Ropeway: Given the land’s non-forest nature, RTDC and the state will not require permission from MoEFCC" (Nov 18, 2025) 4. "How the centuries-old Jodidara tradition is fading in Himachal’s Trans-Giri region: Jodidara: a form of fraternal polyandry—has long been part of Hatti tribal culture in the Trans-Giri region of Himachal Pradesh and adjoining Uttarakhand. It is believed to have evolved to prevent division of ancestral land and maintain unity among brothers in the harsh, mountainous terrain" (Aug 18, 2025) Legal & Agricultural Affairs "Kisan Sabha hails SC’s setting aside Himachal HC order to remove orchards from forest land" (Dec 18, 2025): Covering a major Supreme Court victory for farmers, where a High Court order to remove fruit-bearing apple orchards was overturned. "Himachal Cabinet nod to new tourism policy; focus on home-stays in tribal areas" (Dec 11, 2025): Detailing the legislative push to decentralize tourism and bring economic benefits to Lahaul-Spiti and Kinnaur. 3. Governance & Environment "Forest rights and development: Why Himachal is seeking more leeway from Centre" (Dec 19, 2025): Reporting on the legal hurdles faced by the state in infrastructure projects due to the Forest Conservation Act. "Cloudbursts and resilience: How Himachal’s remote villages are building back better" (Nov 2025): Following up on the long-term rehabilitation efforts after monsoon-related disasters. Crime especially cyber crimes, crypto currency etc: crypto currency: "Agents in uniform, motivational speeches, lavish parties: How a Himachal crypto con went unnoticed:A serial conman, a ‘Nelson Mandela Nobel Peace Award winner', and retired policemen got together to pull off a Rs 1,740-crore fraud" (Nov 10, 2023) Signature Beats Saurabh is recognized for his tenacious reporting on the state's drug epidemic. His deep familiarity with the topography and tribal culture of Himachal allows him to report from remote locations like Spiti, Pangi, Shillai, which are often overlooked by national media. His legal expertise makes him a primary choice for covering the Himachal Pradesh High Court on issues ranging from local body elections to environmental PILs. X (Twitter): @saurabh_prashar . ... Read More

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