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If you are looking for the official U.S. Government forecast for space weather, please go to NOAA's Space Weather Prediction Center ( This "Experimental Research Information" consists of preliminary NASA research products and should be interpreted and used accordingly.

The "Halloween Storms" of 2013

November 5, 2013: Many space weather researchers recall the energetic flares, CMEs and geomagnetic storms of late October/early November 2003 as the most exciting time in recent space weather history. The Sun was in the declining phase of the solar cycle, and forecasters knew of the enhanced threat posed by activity during the declining phase. The "Halloween Storms" of 2003 produced a series of flares, CMEs and energetic particle events , with dramatic geospace impacts that are still being studied today.

Ten years later, in late October 2013, the Sun appeared to be gearing for a repeat of the famous "Halloween Storms." Over the past two weeks, the daily sunspot number peaked at 228, and a series of complex magnetic field regions has produced four X-flares, 9 CMEs with speed > 900 km/sec, and increased solar energetic particle activity. Although none of these eruptions have had an impact comparable to the 2003 storms, there are still sunspot regions on the Sun that are likely to continue producing X-flares and energetic eruptions, including a large "beta-gamma-delta" region that will be pointed toward Earth in the next couple of days.

These sunspot regions will almost certainly have an impact on our assessment of the magnitude and timing of "solar maximum." Although the sunspot number in the northern hemisphere of the Sun appears to have reached its peak and is in the declining phase, the southern hemisphere has clearly not "maxed out" yet. This "second wind," combined with the well-documented space weather impacts associated with the declining phase of the solar cycle, indicate that this solar cycle may have many more interesting space weather events to come.

Mid-month update: The Sunspot Number for 15 November 2013 is 234, and this month is on track to have the highest average sunspot number for the current solar cycle. The sunspot activity over the past couple of months may indicate that we have not reached solar maximum. iSWA's new Solarscape Viewer allows you to view the sunspot regions and also determine whether any of them are magnetically "connected" to Earth.

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