“THE SOLAR WIND travel time from the Sun to the Earth is of the order of 80 hours, while solar wind monitors at the first Lagrangian point (L1), 1.4 million km from the Earth, provide measurements of the incoming solar wind that reaches the outer edges of the magnetosphere within about 40 minutes to 1 hour of their detection.”
https://link.springer.com/article/10.12942/lrsp-2007-1