Whether or not the upcoming cycle 24 of solar activity will be strong is being hotly debated. The solar cycle is produced by a complex dynamo mechanism. We model the last few solar cycles by “feeding” observational data of the Sun’s polar magnetic field into our solar dynamo model. Our results fit the observed sunspot numbers of cycles 21–23 reasonably well and predict that cycle 24 will be about 35% weaker than cycle 23.

Although systematic measurements of the Sun's polar magnetic field exist only from mid‐1970s, other proxies can be used to infer the polar field at e