Mithilanchal · Middle & Lower Gangetic Plain
Terrain and eco-zones
Humid subtropical with a heavy monsoon — 1,200 to 1,500 mm, more in the terai, and most of it in ten weeks. The plain is close to sea level and drains badly, so the water stays. January nights fall to 7–9 °C with dense fog; May and June reach 40–42 °C with high humidity.
Landforms
Flat, young Gangetic alluvium with almost no gradient — under 15 cm per kilometre in placesChaurs — permanent shallow wetlands in the abandoned channels of rivers that have moved onPokhar and talab — tens of thousands of dug ponds, most of them centuries oldKosi megafan, one of the largest river fans in the world, built of the sediment the river drops as it leaves the hillsTerai marsh and grassland at the foot of the Himalaya
Rivers and waters
Kosi — the Sorrow of Bihar, which has shifted its course over 100 km westward in two centuriesKamla, Balan and Bagmati, all Himalayan-fed and all prone to sudden riseGandak — the western boundaryGanga — the southern boundaryAdhwara group, a braid of small streams that flood the Sitamarhi plain
Through the year
| Season | Months | Typical | What it is like |
|---|---|---|---|
| Winter | November–February | 7–24 °C | Cold, foggy and the region's working season — makhana processing, weddings, Sama-Chakeva and the Kartik Chhath just before it. |
| Summer | March–June | 25–42 °C | Hot and humid, with mango and litchi from May. Makhana seeds are collected from the pond beds in this season by divers. |
| Monsoon | July–September | 27–35 °C | Flood season. Large parts of the Kosi districts go under water for weeks; village life shifts to embankments and boats, and the Jat-Jatin songs are sung. |
| Post-monsoon | October | 22–32 °C | The water falls, paddy ripens, and the festival season opens with Durga Puja and Chhath. |
Best time to visitNovember to February. Vivaha Panchami at Janakpur falls in late November or early December, Sama-Chakeva runs through Kartik, and Chhath in October or November is when the region is at its fullest — and its most crowded, because everyone working elsewhere comes home for it.
The climate, landforms, rivers and seasons of Mithilanchal, and the best time of year to visit. (4)