Seneca is a small town located in Grant County, Oregon. It experiences a semi-arid climate with hot, dry summers and cold winters. Summers are characterized by high temperatures reaching up to the mid-80s Fahrenheit (around 29°C), while winters are cold with average lows in the mid-20s Fahrenheit (around -4°C). Precipitation is relatively low throughout the year, with an annual average of around 16 inches.

The hydrology constituents in Seneca primarily consist of the Silvies River, which flows nearby. This river provides important water resources for the town and supports various aquatic species.

Seneca offers several outdoor recreation opportunities. The nearby Malheur National Forest provides numerous hiking trails through beautiful scenery, allowing visitors to explore the stunning mountain landscapes. The Silvies River is also popular for fishing, offering opportunities to catch trout and other species. Additionally, the area is known for its abundant wildlife, making it a great spot for birdwatching and wildlife photography. Overall, Seneca provides a peaceful and scenic backdrop for outdoor enthusiasts to indulge in various recreational activities.