What does this number mean?
Bz is the north-south part of the magnetic field carried by the solar wind. Positive values point north; negative values point south. The reading is measured in nanotesla (nT).
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IMF Bz & the Solar Wind Magnetic Field
IMF Bz is the north–south component of the interplanetary magnetic field carried by the solar wind. Explore recent nanotesla readings and the difference between brief dips and sustained southward conditions.NOAA observed readings
IMF Bz
Latest graphed reading: -2.2 nT on Nov 7, 2026, 12:15 PM EST.
NOAA reading 1-hour average
View readings as a table
| Date and time (Eastern) | IMF Bz |
|---|---|
| Nov 7, 12:15 PM EST | -2.2 nT |
| Nov 7, 12:00 PM EST | -2.7 nT |
| Nov 7, 11:45 AM EST | -7.5 nT |
| Nov 7, 11:30 AM EST | 0.3 nT |
| Nov 7, 11:15 AM EST | 5.3 nT |
| Nov 7, 11:00 AM EST | 7.4 nT |
| Nov 7, 10:45 AM EST | 9.9 nT |
| Nov 7, 10:30 AM EST | 4.5 nT |
| Nov 7, 10:15 AM EST | 8.3 nT |
| Nov 7, 10:00 AM EST | -2.0 nT |
| Nov 7, 9:45 AM EST | 3.4 nT |
| Nov 7, 9:30 AM EST | 9.1 nT |
| Nov 7, 9:15 AM EST | 7 nT |
| Nov 7, 9:00 AM EST | 10.9 nT |
| Nov 7, 8:45 AM EST | 8.8 nT |
| Nov 7, 8:30 AM EST | 7.6 nT |
| Nov 7, 8:15 AM EST | 9.8 nT |
| Nov 7, 8:00 AM EST | 1.6 nT |
| Nov 7, 7:45 AM EST | 2.7 nT |
| Nov 7, 7:30 AM EST | -5.0 nT |
| Nov 7, 7:15 AM EST | -0.2 nT |
| Nov 7, 7:00 AM EST | 9.9 nT |
| Nov 7, 6:45 AM EST | 8.7 nT |
| Nov 7, 6:30 AM EST | 8.2 nT |
| Nov 7, 6:15 AM EST | 4.9 nT |
| Nov 7, 6:00 AM EST | 9.7 nT |
| Nov 7, 5:45 AM EST | 5.1 nT |
| Nov 7, 5:30 AM EST | 5.5 nT |
| Nov 7, 5:15 AM EST | 6.8 nT |
| Nov 7, 5:00 AM EST | 0.3 nT |
| Nov 7, 4:45 AM EST | -1.9 nT |
| Nov 7, 4:30 AM EST | -4.6 nT |
| Nov 7, 4:15 AM EST | -4.3 nT |
| Nov 7, 4:00 AM EST | 6.6 nT |
| Nov 7, 3:45 AM EST | 4.0 nT |
| Nov 7, 3:30 AM EST | -5.9 nT |
| Nov 7, 3:15 AM EST | 6.8 nT |
| Nov 7, 3:00 AM EST | 2.2 nT |
| Nov 7, 2:45 AM EST | -0.3 nT |
| Nov 7, 2:30 AM EST | 4.3 nT |
| Nov 7, 2:15 AM EST | 6.9 nT |
| Nov 7, 2:00 AM EST | 5.1 nT |
| Nov 7, 1:45 AM EST | 6.0 nT |
| Nov 7, 1:30 AM EST | -6.7 nT |
| Nov 7, 1:15 AM EST | -7.5 nT |
| Nov 7, 1:00 AM EST | -6.0 nT |
| Nov 7, 12:45 AM EST | 5.0 nT |
Readings: NOAA real-time magnetic field product. Times are shown in Eastern time. The graph keeps the latest reading in each 15-minute period. Missing measurements are left blank, not treated as zero. The optional 1-hour average is calculated here from consecutive readings.
Why does it matter for HF?
Sustained southward (negative) Bz makes it easier for energy from the solar wind to enter Earth's magnetic environment. This can raise geomagnetic activity and affect HF reliability.
How should I use the graph?
Watch how long Bz stays negative, especially when solar-wind speed is elevated. A brief dip is less informative than a sustained change; check Kp to see how Earth's field responds.
Learn more from NOAA Space Weather Prediction Center and ARRL's HF propagation guide.