Go Beyond a Basic Forecast
Planning a trip to the mountains during the rainy season requires more than just checking if rain is predicted. The most significant dangers in hilly terrain are not the showers themselves but their consequences: landslides and flash floods. A generic
forecast might say “cloudy with a chance of rain,” but this doesn’t provide the actionable information needed to assess the actual risk on the ground. To make informed decisions, you need to dig deeper into the specifics of the weather forecast, moving beyond a simple yes/no for precipitation. The key is to understand the intensity, duration, and potential impact of the expected rainfall.
Focus on Rainfall Intensity
The single most important piece of information is not how much it will rain, but how hard and for how long. Experts note that rainfall intensity—measured in millimetres per hour—is a critical factor in triggering landslides. Soil can only absorb water at a certain rate; when rainfall is extremely intense, the excess water runs off, eroding slopes and adding immense weight to the soil, which can lead to slope failure. A forecast that predicts 100 mm of rain over 24 hours is very different from one that predicts 100 mm in just two or three hours. The latter, a short, intense burst, is far more likely to trigger a flash flood or a landslide. Look for forecasts that provide details on expected rainfall intensity, sometimes categorised as heavy, very heavy, or extremely heavy rainfall.
Understand IMD Colour-Coded Alerts
The India Meteorological Department (IMD) uses a four-colour-coded alert system to communicate the severity of expected weather, which is crucial for travellers. A Green alert means “No Warning,” indicating stable weather. A Yellow alert means “Be Aware”; it's a watch-out signal suggesting weather could worsen and you should stay updated. An Orange alert means “Be Prepared.” It is issued when heavy to very heavy rain is likely, and warns of potential disruptions like traffic jams, waterlogging, and travel delays. A Red alert means “Take Action.” This is the highest level of warning, issued for extremely severe weather conditions that pose a significant threat to life and property, often involving extremely heavy rainfall and a high risk of floods and landslides. Travelling to or within a region under an Orange or Red alert is strongly discouraged.
Check for Landslide and Flash Flood Warnings
Beyond general rain alerts, look for specific advisories related to landslides and flash floods. These warnings are often issued by local or district-level disaster management authorities based on IMD forecasts and ground conditions. Continuous rainfall over several days can saturate the ground, making landslides possible even without a single intense downpour. Remember that landslide risk is highly localised and depends on factors like slope steepness, soil type, and recent construction activity. Several government bodies, including the Geological Survey of India, provide landslide susceptibility maps that can give you a general idea of which areas are more vulnerable. Always heed local advice, as residents and authorities will have the most current information about specific roads or trails that are at risk.
Use Real-Time and Localised Information
Mountain weather is notoriously fickle and can change rapidly. While a five-day forecast is good for initial planning, you must check for real-time updates just before and during your trip. Use weather apps that provide live radar maps to track the movement of rain showers. Some reliable apps for the Indian subcontinent include the IMD's official 'Meghdoot' app, alongside others like Skymet Weather and AccuWeather. Additionally, stay connected with local sources. Before starting a road journey, check with local police or transport authorities about road conditions. Many travel forums and social media groups also provide real-time updates from fellow travellers on the ground, which can be invaluable for avoiding routes that have been recently affected by weather.
