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Solar Cycle Progression and Forecast

Marshall Space Flight Center

Marshall Solar Cycle Forecast

The Space Environments Team in the Natural Environments Branch of the Engineering Directorate at Marshall Space Flight Center (MSFC) provides solar cycle predictions for NASA engineering programs and the aerospace community.

The purpose of the predictions is to provide future statistical estimates of sunspot number, solar radio 10.7 cm flux (F10.7), and the geomagnetic planetary index, Ap, for input to various space environment models. For example, the F10.7 and Ap are required inputs to upper atmosphere (thermosphere) density computer models used for spacecraft operations such as orbital lifetime analysis and for the planning of future spacecraft missions.
        Each month the solar prediction is updated using historical and the latest month’s observed solar indices to provide estimates for the balance of the current solar cycle and the next. The forecasted solar indices represent the 13-month smoothed values consisting of a best estimate value stated as a 50 percentile value along with the 95 and 5 percentile statistical values. The F10.7 prediction also includes a 75 percentile value. 
        The estimation technique is used to predict the remaining of the current cycle, but it is not able to predict the next solar cycle at this time. However, for engineering applications and mission planning an extended forecast for the next solar cycle is given below. The values shown for the next cycle are those of a mean cycle obtained from averaging previous cycles of 13-month smoothed indices along with the calculated statistical bounds.

Updated 11 September 2023

Sunspot Number

Sunspot Number Extended Forecast:    Plot   |   Table 

Sunspot Number Recent Observations:   Table  (Monthly & 13-Month Smoothed) 

Radio Flux

Radio Flux (10.7 cm) Extended Forecast:   Plot  | Table (95 percentile)  | Table (75 percentile) 

Radio Flux Recent Observations:  Table  (Monthly & 13-Month Smoothed)

Geomagnetic Index Ap

 Geomagnetic Index Ap Extended Forecast:  Plot  | Table 

Geomagnetic Index Ap Recent Observations:  Table   (Monthly & 13-Month Smoothed) 

Archived Forecast

See data from 1999 through present day.

Learn More about Archived Forecast

Marshall Solar Cycle Forecast Data Sources

The monthly mean data presented in Solar Cycle Progression and Forecast and used in generating the forecast products are obtained from the sources listed below.

Sunspot Number:

NASA's Solar Dynamics Observatory observed a large sunspot, source of a powerful solar flare (an X 9.3) and a coronal mass ejection (Sept. 6, 2017). The flare was the largest solar flare of the last decade.

Solar Radio Flux (0.7cm):

Ap Geomagnetic Index:


Ronnie J. Suggs
Marshall Space Flight Center

Dr. Anthony DeStefano
Marshall Space Flight Center