IMD rainfall categories explained, with Kota examples

IMD rainfall categories are the words behind every monsoon warning you read for Kota: “heavy rain at isolated places”, “very heavy rainfall likely”, “extremely heavy falls”. Each phrase has a precise meaning in millimetres, set by the India Meteorological Department (IMD). Knowing those numbers, and how they compare with Kota’s normal rainfall, helps you judge how seriously to take a warning and what to expect on the ground. This guide explains the categories, the definition of a rainy day, and what each level means in Kota.

This page explains terms; it does not forecast. For warnings in force, see the IMD district warnings map and our Kota weather warnings guide.

The categories in millimetres

IMD classifies rainfall at a station by the amount recorded in 24 hours:

Category	Rain in 24 hours
Very light / trace	Below 2.5 mm
Light	2.5 to 15.5 mm
Moderate	15.6 to 64.4 mm
Heavy	64.5 to 115.5 mm
Very heavy	115.6 to 204.4 mm
Extremely heavy	204.5 mm or more

Source: IMD bulletin legends (heavy, very heavy and extremely heavy bands as used in IMD bulletins).

The boundaries look odd, but they roughly match round numbers in inches: 64.5 mm is about 2.5 inches, 115.6 mm about 4.5 inches and 204.5 mm about 8 inches. You may see press reports round them differently; for exact limits, use the legend on IMD bulletins.

IMD’s daily rainfall is normally the total for the 24 hours ending at 08:30 IST, so heavy overnight rain appears in the next morning’s figures.

What is a rainy day?

In IMD climate statistics, a rainy day is a day with at least 2.5 mm of rain, the bottom of the “light” category. A brief sprinkle that only wets the ground does not count.

By that definition Kota Airport averages 38.6 rainy days a year in the 1991-2020 normals: 4.7 in June, 11.6 in July, 11.2 in August and 5.8 in September, and less than one in every other month. In other words, even in July, the wettest month, roughly two days in three are not rainy days. See Kota rainfall for the full monthly table.

Putting the categories in Kota context

Comparing a single day’s rain with Kota’s monthly normals shows why the upper categories matter:

Kota normal	Amount
Average July rainfall	296.7 mm
Average August rainfall	269.6 mm
Average September rainfall	108.7 mm
Average June rainfall	80.3 mm
Average annual rainfall	816.2 mm

Source: IMD 1991-2020 normals for Kota Airport.

• A heavy rain day (64.5 to 115.5 mm) can bring as much as a whole normal June, or a whole normal September at the top of the range.
• A very heavy rain day (115.6 to 204.4 mm) can bring between about 40 and 70 percent of an average July in 24 hours.
• An extremely heavy rain day (204.5 mm or more) delivers about a quarter of Kota’s whole normal year in a single day.

Monsoon rain in Kota tends to arrive in spells rather than as steady drizzle, so a month’s total is often made up of a few very wet days and many dry or light ones. That is why a single very heavy or extremely heavy day can cause waterlogging, overflowing drains and road closures even in a month that ends up near normal. See Kota monsoon.

What each level usually means on the ground

These are general descriptions, not guarantees; local drainage, the duration of the rain and what fell on previous days all matter.

• Light and moderate rain: wet roads, slower traffic, puddles. Normal monsoon life.
• Heavy rain: water collecting in low-lying roads and underpasses, slow traffic and possible short power cuts. Plan extra travel time.
• Very heavy rain: waterlogging in many low areas, disrupted local transport, possible damage to weak structures. Avoid unnecessary travel and keep away from drains and streams.
• Extremely heavy rain: serious flooding is possible. Follow official advice closely.

In Kota there is a second factor: rain in the wider Chambal basin upstream. Heavy rain over the catchment can fill the dams and lead to water releases through Kota Barrage, even if the city itself has had less rain. Our Kota Barrage flood season guide explains how that works and who announces gate openings.

What an average rainy day in Kota looks like

Dividing IMD’s normal monthly rainfall for Kota Airport by the number of rainy days (2.5 mm or more) gives a rough idea of how much falls on a typical wet day:

Month	Normal rainfall	Rainy days	Average per rainy day
June	80.3 mm	4.7	about 17 mm
July	296.7 mm	11.6	about 26 mm
August	269.6 mm	11.2	about 24 mm
September	108.7 mm	5.8	about 19 mm

All four averages sit in IMD’s “moderate” band. In reality, rain is uneven: many wet days bring only light rain, and a few heavy or very heavy days supply a large share of the monthly total. That is why one or two orange-alert days can decide whether a month ends above or below normal. Month-by-month detail is in our guides to Kota weather in July, August and September.

How IMD phrases warnings

IMD warnings combine the rainfall category with how widespread it is expected to be. Phrases like “at isolated places” or “at a few places” mean the heavy rain is expected at some locations within the district, not everywhere. Warnings are also colour-coded:

• Green: no warning.
• Yellow: be aware and stay updated.
• Orange: be prepared for disruption.
• Red: take action; severe impacts are expected.

Kota weather warnings explains the colour codes in more detail, and Kota lightning safety covers the thunderstorms that often come with heavy rain.

Seasonal categories: normal, deficient, excess

IMD uses a second set of words for whole seasons rather than single days. During and after the monsoon, district and state rainfall is compared with the long-period average and labelled by its departure from normal:

Category	Departure from normal
Large excess	60 percent or more above
Excess	20 to 59 percent above
Normal	Within 19 percent either way
Deficient	20 to 59 percent below
Large deficient	60 to 99 percent below
No rain	100 percent below

So when you read that Kota district is “deficient” in mid-August, it means the season’s rain so far is at least a fifth below the normal for those dates, not that no heavy rain has fallen. A season can be normal overall and still include damaging very heavy rain days, or be deficient despite one extreme downpour.

Checking how much rain actually fell

After a heavy rain event, IMD’s regional centre in Jaipur publishes station rainfall reports for Rajasthan, and IMD’s national products show district-wise rainfall and departures from normal for the season. Those are the authoritative record, rather than social media totals. For the live forecast before the rain, see Kota weather forecast.