Every 7-day weather forecast is a rolling window updated multiple times a day by numerical weather-prediction models. It stitches together data from surface weather stations, upper-air balloons, satellite radiometers, doppler-radar returns and ocean buoys, then runs the mix through supercomputer models to project the atmosphere seven days out. In India the primary authority is the India Meteorological Department (IMD) — the agency responsible for weather forecasts, cyclone warnings and monsoon updates across all Indian states.

For each day the forecast gives a high temperature (day max), a low temperature (night min), a rain probability, expected rainfall in millimetres, wind speed and direction, humidity band and a UV index. Read the seven cards left-to-right as a story: which day is coolest, which day carries the highest rain risk, and which day is safe to plan an outdoor event on.

A live 7-day outlook is especially useful in cities with sharply seasonal weather. In coastal Mumbai, Chennai and Kochi, watch rainfall probability during monsoon (June–September) for heavy-rain and waterlogging alerts. In inland Delhi, Jaipur and Lucknow, summer is dominated by heat-wave watches (day max above 42°C) and winter by cold-wave and dense-fog warnings that hit road, rail and flight schedules. In the hills — Shimla, Manali, Darjeeling, Gangtok — the outlook helps trekkers and drivers spot snow, hail and landslide-prone rainfall. In Bengaluru, Hyderabad and Pune, watch for pre-monsoon thunderstorms and flash rain.

Rain probability is not a rain guarantee — a 60% chance means six in ten model runs produced measurable rain at that location on that day. Treat any day with a rain probability above 50% and rainfall over 15 mm as a serious wet-day plan. High wind combined with heavy rain is the signal to postpone outdoor events and open-air deliveries.

Temperature bands matter: a 6–8°C day-to-night gap tells you to layer, while a narrow 2–3°C band usually signals cloud cover and higher humidity. The UV index tells you sun-exposure risk — above 8 is very-high and calls for sunscreen, hat and hydration. Air-quality index (AQI) is a separate but paired metric — check it especially in Delhi, Ghaziabad, Noida and Kolkata during winter.

Rely on official government sources first. The IMD website publishes district-level forecasts, cyclone bulletins and heat-wave alerts. The Mausam app (IMD’s official mobile app) delivers the same forecast on Android and iOS. For app-based alerts and radar imagery, Windy, AccuWeather, The Weather Channel, Google Weather and Apple Weather all serve accurate 7-day forecasts backed by ECMWF, GFS or blended-model data. Cross-check any single source against IMD before making a major decision.

How accurate is a 7-day forecast? Day-1 and Day-2 forecasts are 85–90% accurate for temperature and 75–80% for rainfall. Accuracy tapers off gradually toward Day-7 — trust the near-term days more than the far-end ones.

Why do two apps show different numbers? Different apps run different weather-prediction models (ECMWF, GFS, ICON, IMD-GFS) and different local downscaling logic. Small day-to-day differences are normal; the trend direction is what matters.