Solar Cycle Science Discover the Sun!

Discover the Predictions!

This page features our predictions and forecasts for the Sun. Currently, we have Solar Cycle predictions for Solar Cycles 24 and 25 (cycle amplitude and F10.7 flux). We also show our predictions for the evolution of the Sun's polar magnetic fields for the endof Solar Cycle 24, which were used to predict the amplitude of Cycle 25.
Cycle 24/25 Minimum can now be identified as occurring in December 2019 with a smoothed sunspot number (V2.0) of 1.8.  The smoothed sunspot number for January 2020 was higher and the smoothed number of spotless days per month was lower. Cycle 25 is underway as evidenced by the increasing number of high latitude sunspot groups and changes in the axisymmetric flows seen since mid-2019 (see the sunspot area butterfly diagram the differential rotation history and the meridional flow history).

Discover the Cycle 24/25 Predictions!

Predicting the behavior of a sunspot cycle is fairly reliable once the cycle is well underway. Former MSFC Solar Physics Branch members Wilson, Hathaway, and Reichmann have studied the sunspot record for characteristic behavior that might help in predicting future sunspot activity. Among the most reliable techniques are those that use the measurements of changes in the Earth's magnetic field at, and before, sunspot minimum, e.g. "geomagnetic precursors".  Details can be found in two papers here and here.

The prediction for Sunspot Cycle 24 gave a smoothed sunspot number V2.0 maximum of about 101 in late 2013. The smoothed sunspot number V2.0 reached a peak of 116.4 in April 2014. This has become the official maximum. This second peak surpassed the level of the first peak (98.3 in March 2012). Many cycles are double peaked but this is the first in which the second peak in sunspot number was larger than the first. We are currently nearing the end of Cycle 24. The predicted and observed size makes this the smallest sunspot cycle since Cycle 14, which had a maximum smoothed sunspot number V2.0 of 107.2 in February of 1906.

We predict that Cycle 25 will be another small cycle, with an amplitude slightly smaller than (~95-97%) the size of Cycle 24. Weak cycles such as this are preceded by long extended minima and we expect a similar deep, extended minimum for the Cycle 24/25 minimum in 2020. Based on this solar cycle 25 prediction, we expect that the coming minimum will last through the end of 2020 or into beginning of 2021. Similarly, we expect that the Cycle 24/25 minimum will include extended periods of spotless days throughout 2020 and into 2021. Details about this predictions can be found in this paper.
Our latest solar cycle prediction. The prediction data used to make this plot is in this text file.
Another indicator of the level of solar activity is the flux of radio emission from the Sun at a wavelength of 10.7 cm (2.8 GHz frequency). This flux has been measured daily since 1947. It is an important indicator of solar activity because it tends to follow the changes in the solar ultraviolet that influence the Earth's upper atmosphere and ionosphere. Many models of the upper atmosphere use the 10.7 cm flux (F10.7) as input to determine atmospheric densities and satellite drag. F10.7 has been shown to follow the sunspot number quite closely and similar prediction techniques can be used. Our predictions for F10.7 are available in a text file and as a png image. Current values for F10.7 can be found at:
Solar Cycle 24 and 25 F10.7 Flux Prediction.The data used to make these plots are located in this text file.

Discover the Cycle 24 Polar Field Predictions!

We have used our AFT code to predict the amplitude and hemispheric asymmetry of the Sun’s polar magnetic fields at the start of 2020, approximately the next cycle minimum. (Recall that observations have shown that the strength of the polar fields is a good indicator of the strength of the next cycle.) While we do not know the details of the active region sources and transport flows that will occur between now and then, we use knowledgeable estimates, along with their known variability, to produce a series of 32 realizations for the evolution of the Sun’s surface magnetic field from the end of January 2016 to the start of January 2020. More information about these predictions can be found in this paper.
Solar Cycle 24 Polar Field Predictions. The left plot shows 16 predictions with 8 variations in the convective flow pattern and 2 variation in the meridional flow profile. The right plot shows 16 predictions with 8 variations in the Joy's Law tilt and 2 variation in the meridional flow profile. All 32 realizations predict the polar fields for the coming minumun will be similar in strength (or slightly weaker) than the polar fields that were seen during the last solar minimum.

In 2019 we updated our simulations with the through the beginning of 2019 and repeated our simulations. More information about these updated predictions can be found in this paper.
AFT 2018 predictions and observations to date. This figure shows the polar field observations (red) along with the AFT predictions (2016 in the lighter blue and 2018 in the darker blue). The polar fields strengths as measured from 55° and above are shown on the top. The polar field strength as measured from the axial dipole moment is shown on the bottom. Observations since these predictions were made are in agreement.