Where is the Coriolis effect weakest?

At the equator, the Coriolis force is zero and the wind blows perpendicular to the isobars. There is no Coriolis effect because there is no turning of the surface of the Earth (sense of rotation) underneath a horizontally and freely moving object at the equator. The object’s path is straight and there is no curving of the object’s path as measured relative to Earth’s surface. The object’s path is straight

Further Reading:

• Forces Affecting Velocity And Direction Of Wind
• Types of Wind