The India Meteorological Department (IMD) issues weather warnings using a four-colour code: green, yellow, orange and red. The colours are a shorthand for how severe the expected weather is and how much people and authorities should do about it. In Uttarakhand, where slopes are steep and rain-loosened ground fails easily, reading them correctly is worth the few minutes it takes.
Green means no warning is in force — no action is needed. Yellow means "be aware": potentially hazardous weather is possible, and you should stay updated. Orange means "be prepared": authorities and the public should get ready for disruption, because significant weather is likely. Red means "take action": extremely heavy or dangerous weather is expected, and the safest choice is usually to avoid travel and follow official instructions.
The colours are anchored partly in rainfall amounts. Over a 24-hour period, IMD classes rain of 64.5 to 115.5 millimetres as "heavy", 115.6 to 204.4 millimetres as "very heavy", and anything above that as "extremely heavy". But the colour is not decided by rainfall alone — it also reflects the likely impact, given the terrain and how vulnerable an area already is.
That distinction matters in the hills. In Uttarakhand, a yellow or orange alert can still precede serious trouble, because ground that is already saturated needs far less rain to slide, and because a single stretch of highway blocked by debris can cut off a whole valley. The impact of a given amount of rain here is simply larger than the same rain falling on flat, well-drained land.
Cloudbursts are the hardest case. They are intense, highly localised downpours that current forecasting cannot pin down to a specific village in advance. A colour alert flags the broad risk of extreme rain over a region; it cannot say which stream will flood. This is why, during an orange or red alert, official advice leans toward caution across an entire area rather than waiting for certainty about one location.
The practical takeaway is to match your response to the colour. On yellow, stay informed and check road conditions before setting out. On orange, prepare for disruption and reconsider non-essential travel on hill routes. On red, treat travel as unsafe unless authorities say otherwise, and follow the instructions of the district administration and the SDRF.