Across the 34 years of record to 2024, the monsoon's first sustained rain reaches Dehradun around 18 June on average. That is an average, not a forecast for this year.
In half of those years it arrived between 11 June and 26 June. That 16-day window is the number worth planning around. The date moves enough from year to year that the average alone is a poor guide.
Common questions about the monsoon in Dehradun
When will the monsoon reach Dehradun?
Around 18 June on average, and between 11 June and 26 June in half of years. The exact date in any single year cannot be known in advance; the window can.
When does it rain in Dehradun?
83% of the 1361 mm this city receives in a year falls between June and September. July is the wettest month — 416 mm across about 28 days of rain.
How long does the monsoon last in Dehradun?
About 105 days, with withdrawal around 1 October.
What changes when it arrives
The clearest change is heat. May averages a daily maximum of 33.6°C; by July that has fallen 4.6°C. Rain days rise too: roughly 88 days of rain across June to September.
The last 12 years
This is Dehradun's own record, not a regional average.
| Year | Monsoon onset | Withdrawal | Days |
|---|---|---|---|
| 2013 | 6 June | 16 October | 132 |
| 2014 | 30 June | 18 September | 80 |
| 2015 | 16 June | 2 October | 108 |
| 2016 | 12 June | 30 September | 110 |
| 2017 | 22 June | 3 October | 103 |
| 2018 | 30 May | 3 October | 126 |
| 2019 | 1 July | 7 October | 98 |
| 2020 | 29 June | 8 September | 71 |
| 2021 | 7 July | 27 October | 112 |
| 2022 | 15 June | 20 October | 127 |
| 2023 | 16 June | 24 September | 100 |
| 2024 | 22 June | 5 October | 105 |
Where these numbers come from
Source: Open-Meteo's historical weather archive, whose default model blends ERA5 and ERA5-Land reanalysis with ECMWF IFS HRES from 2017 — 1991-2024 (34 years). Open-Meteo offers no rainfall from ERA5-Land, so the rain figures come from ERA5 and IFS. Temperatures are monthly averages of daily highs and lows; rainfall is the average monthly total. A grid estimate can differ from a local weather station. The grid point used for Dehradun sits about 6 km from the city. Onset dates are worked out from the same source's daily rainfall.
Our definition of onset is the first day on or after 1 May on which the five days starting that day bring at least 20 mm of rain, the ten days after those bring at least 30 mm, and each of the three ten-day periods starting that day brings at least 20 mm. The last condition is there to screen out cyclones; it was added after an earlier version of the rule recorded cyclone Tauktae, in May 2021, as the monsoon's arrival in four cities hundreds of kilometres apart. It narrows that problem without removing it: where a cyclone's rain runs straight into a wet June, the rule can still return a May date. Withdrawal is the last day of the last ten-day period, starting between 1 June and 30 November, that brings at least 20 mm.