What IMD's yellow, orange and red alerts mean for a Ghats road trip

Short answer first. An IMD colour is a forecast of how much rain a district may get in 24 hours, with a matching action word. Yellow means watch, orange means be alert and prepared, red means take action. The rainfall bands are 64.5 mm to 115.5 mm for yellow, 115.6 mm to 204.4 mm for orange and over 204.5 mm for red, as set out in an explainer of IMD's system. Kerala's own disaster management authority publishes the same bands on its rainfall alert page, with red for anything above 204 mm in 24 hours. None of those colours says a single word about whether Shiradi, Charmadi or the Thamarassery climb is open.

What the colours actually stand for

On IMD's subdivision and district warning pages the four steps are written out as No Warning, Watch, Alert and Warning. IMD's public API confirms the mapping behind the map colours: code 1 is red, 2 is orange, 3 is yellow and 4 is green. So a red block over Kozhikode or Udupi is IMD telling the district administration that extremely heavy rain is likely somewhere in that district on that day.

That "somewhere" matters. The warning is issued at district scale and often applies to isolated places inside it. A red day in Dakshina Kannada can mean a coastal taluk gets 250 mm while the ghat section stays wet but passable, or the reverse.

Why red does not mean the ghat is shut

District warnings on IMD's pages run from Day 1 to Day 5, so what you see on Monday for Friday is a five day outlook that will be revised. The short range product is the nowcast, issued separately for districts and stations with a "valid upto" time, and that is the one worth refreshing from a chai stop. Nowcast rain categories are measured in mm per hour, not per 24 hours, which is why a nowcast and a district colour can look like they disagree.

Closures are a separate decision, taken by the district administration, police and the highway agency after landslips, rockfall or fallen trees. IMD does not close roads. A red alert with no landslide can leave a ghat fully open, and a clear yellow day can still bring a slip down on a cut slope that was soaked the week before.

What the alert should change in your plan

Kerala's state authority spells out the instructions that matter most to anyone on a bike or in a 4x4. Avoid night travel in hilly areas. Do not cross rivers or streams on foot or on wheels during heavy rain. Do not stop for selfies or crowd on bridges over water bodies. Keep an emergency kit ready and move only in daylight if you have to move at all.

Turned into a trip plan, that means timing the ghat section for mid morning rather than after dark, carrying one buffer day for every three days of riding, filling fuel before the climb instead of after it, and skipping the waterfall stops that cause most monsoon trouble in the Ghats. Download offline maps and write down the alternate route, because Shiradi, Charmadi, Sampaje and Bisle all back each other up at the cost of extra kilometres.

One seasonal note. IMD's press release list records that the southwest monsoon withdrew from the entire country on 15 October 2026, but Kerala and Tamil Nadu keep getting northeast monsoon rain into December. The colours keep coming after the monsoon is officially gone.

Sources

• IMD subdivision wise warnings
• IMD public API reference
• Kerala State Disaster Management Authority rainfall alert page
• Outlook Traveller: IMD's red, orange and yellow alerts explained
• IMD press releases