Southwest monsoon season (June to September) – 2023 rainfall forecast for different districts of Tamil Nadu is developed based on the Southern Oscillation Index and Sea Surface Temperature values of Pacific and Indian Oceans by using Australian Rainman International V.4.3. Software at Agro Climate Research Centre of Tamil Nadu Agricultural University, Coimbatore and is presented at 60% probability level.
Normal Rainfall (±10 percent deviation from long-term mean rainfall) is expected in all the districts of Tamil Nadu.
District level seasonal rainfall forecast for Southwest Monsoon 2023
| S. No | Districts | Normal Rainfall (mm) | Predicted Rainfall (mm) | Per cent deviation |
| 1 | Ariyalur | 377 | 370 | -1.9 |
| 2 | Chengalpattu | 450 | 410 | -8.9 |
| 3 | Chennai | 440 | 460 | 4.5 |
| 4 | Coimbatore | 210 | 190 | -9.5 |
| 5 | Cuddalore | 360 | 390 | 8.3 |
| 6 | Dharmapuri | 392 | 390 | -0.5 |
| 7 | Dindigul | 308 | 330 | 7.1 |
| 8 | Erode | 260 | 250 | -3.8 |
| 9 | Kallakurichi | 410 | 390 | -4.9 |
| 10 | Kancheepuram | 479 | 500 | 4.4 |
| 11 | Kanyakumari | 491 | 510 | 3.9 |
| 12 | Karur | 199 | 210 | 5.5 |
| 13 | Krishnagiri | 375 | 360 | -4.0 |
| 14 | Madurai | 325 | 320 | -1.5 |
| 15 | Mayiladuthurai | 295 | 280 | -5.1 |
| 16 | Nagapattinam | 279 | 270 | -3.2 |
| 17 | Namakkal | 336 | 350 | 4.2 |
| 18 | Perambalur | 279 | 260 | -6.8 |
| 19 | Pudukkottai | 330 | 340 | 3.0 |
| 20 | Ramanathapuram | 135 | 140 | 3.7 |
| 21 | Ranipet | 450 | 430 | -4.4 |
| 22 | Salem | 421 | 430 | 2.1 |
| 23 | Sivaganga | 417 | 420 | 0.7 |
| 24 | Thanjavur | 314 | 300 | -4.5 |
| 25 | Theni | 215 | 210 | -2.3 |
| 26 | Tenkasi | 175 | 170 | -2.9 |
| 27 | Tiruvallur | 456 | 500 | 9.6 |
| 28 | Tiruvarur | 302 | 290 | -4.0 |
| 29 | Tuticorin | 67 | 65 | -3.0 |
| 30 | Tiruchirapalli | 277 | 290 | 4.7 |
| 31 | Tirunelveli | 128 | 120 | -6.3 |
| 32 | Tirupathur | 416 | 410 | -1.4 |
| 33 | Tiruppur | 151 | 140 | -7.3 |
| 34 | Thiruvannamalai | 449 | 450 | 0.2 |
| 35 | The Nilgiris | 875 | 800 | -8.6 |
| 36 | Vellore | 453 | 470 | 3.8 |
| 37 | Villupuram | 405 | 440 | 8.6 |
| 38 | Virudhunagar | 190 | 190 | 0.0 |
