For long, Rajasthan’s deserts and scorching loo winds have symbolised India’s harsh summers. But the ongoing heatwave across north India is revealing a striking and scientifically important trend — several cities of Punjab and Haryana are recording temperatures comparable to, and in some cases even higher than, the desert state’s cities.Weather experts, climate scientists and agriculture specialists have raised concerns over this. Why is this happening and what could be its fallout? We explain.First, northwest India naturally experiences heatwaves around April and May. But the intensity as well as spatial spread of the heatwave this year has raised concerns.Climate scientists at the India Meteorological Department’s Chandigarh centre say that heatwaves are no longer restricted to the western desert regions. The Indo-Gangetic plains, including Punjab, Haryana, Delhi and Uttar Pradesh, are experiencing the phenomenon.Several Indian cities featured among the world’s hottest urban locations during this heatwave. Cities in Uttar Pradesh such as Banda and Prayagraj have recorded temperatures nearing 48°C in recent days.Also Read | Why has this summer been particularly hot?On May 21, Punjab’s Bathinda recorded a maximum temperature of 45.6 degrees Celsius and Haryana’s Sirsa touched 45.8°C. In comparison, major Rajasthan cities recorded relatively lower maximum temperatures — Jaipur 42°C, Jodhpur 41.5°C, Bikaner 44°C and Jaisalmer around 42°C. Even Sri Ganganagar — traditionally among Rajasthan’s hottest places — recorded 45.1°C, lower than Sirsa and Bathinda.So why are Punjab and Haryana heating up?Story continues below this adClimate change is increasing the frequency, duration and severity of heatwaves. But for these two states in particular, there are several other factors that have contributed to this rise in temperatures — including humidity, urbanisation and land-use changes. Here’s a look:The farm and forest factorDr Sutantra Airy, former Director Punjab Agriculture Department believes that decades of wheat-paddy monocropping have altered the ecological balance of Punjab and Haryana.Excessive groundwater extraction, shrinking biodiversity, declining tree cover and large-scale stubble burning even after wheat harvesting in April and May have weakened the region’s natural cooling systems.Bare agricultural surfaces after wheat harvesting absorb solar radiation rapidly, causing land temperatures to rise sharply during May and June, said Airy.Story continues below this adAlso Read | The climate terms you’re hearing this summer, explainedAccording to Manmohan Singh, former director at IMD, Chandigarh, extensive irrigation networks, the ongoing paddy nursery cultivation in Punjab and Haryana, and summer maize cultivation in Punjab are not only putting stress on groundwater and canal systems but also contributing to atmospheric moisture. The increased humidity levels makes temperatures feel harsher.Experts say the disappearance of traditional ponds, trees and green belts around villages has also intensified local heating.Punjab today has the lowest forest cover in India. According to the India State of Forest Report, Punjab’s forest cover is around 3.67% while Haryana’s is around 3.7%. Rajasthan, a desert state, has more forest cover at 4.8–4.9%.Warmer nightsStory continues below this adWhat has particularly alarmed experts is that Punjab and Haryana are not only witnessing extreme daytime heat, but also unusually warm nights. This is a phenomenon that has been observed in other states as well.So why are cities not cooling down?One factor is humidity. Cities in Haryana and Punjab’s Malwa belt are increasingly retaining heat even during nights owing to the increase in humidity mentioned above.Another key factor is what is called the urban heat island effect, when concrete infrastructure in cities absorb heat during the day and retain it through the night.Environmental experts increasingly describe parts of Punjab and Haryana as “heat-trap landscapes.”Story continues below this ad“Rapid urbanisation, highways, industrial clusters, vehicular emissions and declining vegetation are causing heat absorption and slow nighttime release. Concrete surfaces store solar heat during the day and radiate it back during the night, keeping temperatures elevated for longer periods,” said Singh.Also Read | Warmer nights during Indian summers may be more dangerous than heatwaves. Here’s whyCombined with climate change and repeated dry spells, this is making northwestern India increasingly vulnerable to severe and prolonged heatwaves.On the example of Rajasthan, Singh said: “Rajasthan’s atmosphere is generally drier, allowing the surface to cool relatively faster after sunset.” In contrast, Punjab and Haryana are increasingly witnessing trapped heat conditions because of moisture, humidity and concrete expansion,” said Singh.Story continues below this adThis is why 44°C in Punjab often feels more uncomfortable than 44°C in Rajasthan.Singh pointed out that some desert regions of West Asia occasionally remain cooler than parts of north India not just because of low humidity, but also lower population density, planned urban design and comparatively better green infrastructure.A warning for agriculture and public healthExperts at IMD Chandigarh said the rising heat trend is a warning for the future of agriculture, water sustainability and public health in Punjab and Haryana.Agriculture expert and Punjab Cane Commissioner Dr. Amrik Singh said, “Repeated exposure to unusually high temperatures during March and April has already affected wheat productivity in several parts of Punjab and Haryana this year.”NewsletterFollow our daily newsletter so you never miss anything important. On Wednesday, we answer readers' questions.SubscribeStory continues below this adWarm nights are scientifically considered more dangerous during heatwaves because the human body gets less time to recover from the stress of daytime heat.“With temperatures now crossing 45°C in many regions during May, may further intensify due to dairy farming, vegetable cultivation, labour efficiency, and groundwater sustainability in the coming weeks,” said Amrik Singh.He cautioned that if such heatwave conditions continue to occur frequently, they could pose long-term challenges for agriculture and rural livelihoods across north India.