A thick fog blanket has engulfed Delhi and northern India, causing travel delays and chaos. Over 100 flights were delayed at Delhi airport on Friday, PTI news agency reported. Dozens of trains were rescheduled or running late.

India’s weather department predicts foggy conditions will continue for the next few days. Dense fog is common in Delhi and northern India during this cold wave season.

Photos and videos show several cities shrouded in mist and haze. Nine airports, including Delhi, experienced zero visibility on Friday morning, according to the India Meteorological Department (IMD).

Delhi airport issued an advisory, warning passengers of significant delays. “Flights that are not CAT III compliant may get affected,” the airport said, referring to the radar system enabling automatic landings in low visibility.

Several airlines urged travelers to check flight schedules before planning their journeys. IMD considers fog “dense” if visibility drops below 200m and “very dense” if it falls below 50m.

Delhi may experience light to moderate rainfall on 6 January, further lowering temperatures, the weather department said.