IMD publishes daily maximum and minimum temperatures for every district in India. During peak summer, IMD also issues heat-wave watches (day-max 4.5°C above normal for two days) and cold-wave watches (night-min in the plains below 10°C). Google Weather, AccuWeather and Windy all overlay the same observations on a colour-coded map you can pan across.

This guide covers how to read a temperature forecast, what the day-max and night-min really tell you, the hottest and coolest Indian cities to watch, the safety protocol during a heat-wave or cold-wave and the fastest apps for live temperature updates in your city.

A temperature forecast has three numbers you should always look at together: the day maximum (typically hit between 2 pm and 4 pm), the night minimum (typically hit between 4 am and 6 am) and the ‘feels like’ temperature (temperature adjusted for humidity and wind).

The gap between day-max and night-min is called the diurnal range. A narrow diurnal range (2–4°C) usually means overcast and humid; a wide diurnal range (10–15°C) usually means dry, clear-sky conditions — cold desert winter or hot pre-monsoon summer. Reading the diurnal range gives you a fast read of the weather system without looking at any other number.

The hourly temperature curve tells you when to work outside and when to stay indoors. In summer, plan outdoor work before 10 am or after 5 pm; the sun-hour peak between 12 pm and 3 pm is when a 42°C day-max feels like 47°C on skin. In winter, the coldest hour is 4–6 am — plan morning school-runs and gym sessions with that in mind.

In peak summer (April–June), the hottest Indian cities are Churu, Phalodi, Jaisalmer, Bikaner, Nagpur, Vidarbha districts and Titlagarh in Odisha. In peak winter (December–January), the coolest inhabited places are Leh, Kargil, Drass, Manali, Shimla, Auli, Munsyari and Gulmarg.

Every list changes with the day’s weather system, so refresh the top-5 every morning. Cities on the same coast can have completely different day-max because of onshore versus offshore breeze — Chennai and Vizag are both on the east coast but often 4–5°C apart on any given afternoon. Elevation matters too — Ooty and Kodaikanal sit within 200 km of Chennai but average 15–20°C cooler year-round.

IMD Mausam app is the primary official source for city-level temperature. Google Weather gives a fast at-a-glance card on any search. Windy shows a colour-coded temperature map you can pan across the country. AccuWeather gives a ‘RealFeel’ feels-like number that accounts for humidity, wind and sun angle.

IMD’s dedicated Heat-Wave Alerts page lists cities under active watch. During any heat-wave watch, the National Disaster Management Authority publishes state and city Heat Action Plans with specific dos and don’ts, hydration protocols, cooling-centre locations and emergency phone numbers. Bookmark the page for your city in advance.

What counts as a heatwave in India? In the plains, IMD declares a heatwave when day-max hits 40°C+ and is 4.5°C+ above normal for two consecutive days. In coastal areas, day-max 37°C+ with the same departure. In hills, day-max 30°C+ with the departure.

Why does my phone show a ‘feels like’ temperature higher than the actual? ‘Feels like’ combines temperature, humidity and wind. High humidity reduces sweat evaporation, so 32°C at 80% humidity ‘feels like’ 40°C.

How much can day and night temperature differ? In dry desert (Rajasthan) and clear-sky winter, the gap can be 15–20°C. In cloudy humid monsoon, the gap is often only 2–4°C.

What is the highest temperature ever recorded in India? 51.0°C at Phalodi, Rajasthan on 19 May 2016 — the current all-time high for the country, tied with an earlier record from Alwar, Rajasthan (1956, 50.6°C).

What is the lowest temperature ever recorded in India? -45°C at Drass in Ladakh in 1995 — the lowest ever recorded in India and one of the lowest inhabited-place readings in the world.

The ‘feels like’ temperature (or Heat Index / Wind Chill) combines air temperature with humidity in summer and with wind speed in winter to give a more realistic body-perception reading. A 40°C day at 70% humidity ‘feels like’ 51°C on skin because sweat cannot evaporate.

In winter, a 12°C morning with 30 kmph wind ‘feels like’ 6°C. Always read both the actual and the ‘feels like’ when deciding clothing, work-outdoor time and school-uniform layers for children.