On 22 June 2015, a massive coronal mass ejection triggered a strong G4 class geomagnetic storm upon arrival at Earth. This weakened the Earth’s magnetic shield by allowing the reconnection of the interplanetary magnetic field with the geomagnetic field and resulted in the lowering of the cutoff rigidity for incoming cosmic rays, leading to the production of more muons in the atmosphere by extensive air shower phenomena. The GRAPES-3 muon telescope detected this muon burst (E μ >1 GeV) which lasted for two hours with an increase of 50 standard deviations in the muon flux, demonstrating a conclusive anti-correlation (CC=–0.94) with Bz. A recent study with data from the scintillator array of GRAPES-3 confirms the increase in muon flux at a level compatible with that of the muon telescope. Unlike the muon telescope, the scintillators record mainly low energy muons (>MeV) and soft components but lack directional information. A well-situated ground based observatory with precise flux measurements irrespective of the energy domain can enable the detection and forecasting of space weather phenomena.