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Daily Dose · Maps/Sep 23, 2026/Climate · The Monsoon

Thirty-Seven Days to Cross India

As this year's rains begin their retreat — with India 15% short of normal — here is the map of how the southwest monsoon normally arrives: a front of rain that lands in Kerala on 1 June and takes five weeks to reach the last corner of the Thar Desert.

37
days

From onset over Kerala (1 June) to covering the entire country (8 July) — the normal pace of the monsoon's march, per IMD's 1961–2019 normals. The old 1901–40 normal said 15 July.

868.6 mmaverage all-India rain, June–September (IMD LPA, 1971–2020)
of India's annual rain falls in these four months
−15%2026 so far (1 Jun–22 Sep): 706.9 mm vs 832.4 mm normal
70°E 75°E 80°E 85°E 90°E 95°E 10°N 15°N 20°N 25°N 30°N 35°N JUN 5 JUN 10 JUN 15 JUN 20 JUN 30 ARABIAN SEA BRANCH BAY OF BENGAL BRANCH Arabian Sea Bay of Bengal RETREAT BEGINSNORMAL ~SEP 172026: SEP 19 JAISALMER~162 mm/yr MAWSYNRAM 11,871 mm/yr THIRUVANANTHAPURAM · JUN 1 BENGALURU · JUN 3 MUMBAI · JUN 11 PATNA · JUN 16 BHOPAL · JUN 20 AHMEDABAD · JUN 26 DELHI · JUN 27 JAIPUR · JUN 29 BARMER · JUL 5 DIBRUGARH · JUN 4 PORT BLAIR · MAY 21 NORMAL ONSET · MONSOON ARRIVES BY JUN 5 JUN 10 JUN 15 JUN 20 JUN 30 JUL 8 IMD normals, 1961–2019 · schematic
★ Each band = the date by which the monsoon normally arrives. Schematic; isochrones interpolated from IMD normals. Boundaries simplified.
01 · The calendar

A seven-week wave, south-west to north-west

Read the map's colours as a timeline: the Andamans get rain first, the Thar last. Laid flat, the arrival dates form one gradient.

OLD NORMALJUL 15 PORT BLAIRMAY 21 KERALAJUN 1 MUMBAIJUN 11 PATNAJUN 16 BHOPALJUN 20 DELHIJUN 27 ALL INDIAJUL 8

In 2020 IMD replaced its 1901–40 normals. The monsoon now normally covers the country a week earlier (8 July, not 15 July) — but much of central India now gets it 3–7 days later, and it lingers in the north-west more than two weeks longer.

02 · The window

Arrive late, leave early

The places the monsoon reaches last are also the places it abandons first — so the north-west gets the shortest season.

JUN 1 JUL 1 AUG 1 SEP 1 OCT 1 Dibrugarh 132 d Mumbai 119 d Patna 114 d Nagpur 113 d Bhopal 105 d Ahmedabad 94 d Delhi 90 d Jaipur 86 d Barmer 77 d Bikaner 74 d

Bars run from normal onset to normal withdrawal (IMD city normals); day counts derived by Daily Dose. Bar shade: darker = longer season.

03 · The gradient

Seventy-three times wetter, same country

The Khasi Hills catch the Bay of Bengal branch head-on; the Thar sits at the far, tired end of the Arabian Sea branch.

100 mm 1,000 mm 10,000 mm JAISALMER~162 mm · year INDIA · JUN–SEP AVG868.6 mm · season MAWSYNRAM11,871 mm · year LOG SCALE · Mawsynram gets ~73× Jaisalmer's rain
04 · The year

2026: a weak season on a strong run

Five of the last seven seasons finished above normal. This one is tracking the lowest in the series.

IMD "NORMAL" 96–104% 80% 90% 100% 110% 2019 2020 2021 2022 2023 2024 2025 110% 94% 108% 2026* 85%to Sep 22

All-India June–September rainfall as a percentage of the Long Period Average (868.6 mm). IMD calls 96–104% "normal."

*2026 is season-to-date through 22 September (706.9 mm vs 832.4 mm normal for that window), not a final figure. By mid-September, 41% of India's area was rain-deficient. The retreat began from West Rajasthan on 19 September, near the new normal of 17 September.

05 · The stakes

Half the farmland is waiting on this map

Irrigation softens the blow, but much of India still plants when the colour band arrives.

~51%of India's net sown area is rainfed — no irrigation to fall back on.
~40%of India's food production comes from those rainfed fields.
41%of the country's area had deficient rain this season as of 22 Sep 2026.
What to notice on the map

Why it matters

The two arms.Rain arrives on two fronts: the Arabian Sea branch hits Kerala on 1 June; the Bay of Bengal branch floods the northeast by 5 June — before Mumbai sees a drop.

The diagonal.Isochrones run south-west to north-east. The last place to get wet is the Thar, in the far north-west — which is also the first place the rain leaves.

The squeeze.Delhi's normal season is 90 days; Dibrugarh's is 132. The map's colour is also a measure of how long the rain stays.

The spread.From Jaisalmer to Mawsynram, annual rain varies ~73-fold across a single country.

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