Results from the first Sun‐to‐Earth coupled numerical model developed at the Center for Integrated Space Weather Modeling are presented. The model simulates physical processes occurring in space spanning from the corona of the Sun to the Earth's ionosphere, and it represents the first step toward creating a physics‐based numerical tool for predicting space weather conditions in the near‐Earth environment. Two 6‐ to 7‐d intervals, representing different heliospheric conditions in terms of the three‐dimensional configuration of the heliospheric current sheet, are chosen for simulations. These conditions lead to drastically different responses of the simulated magnetosphere‐ionosphere system, emphasizing, on the one hand, challenges one encounters in building such forecasting tools, and on the other hand, emphasizing successes that can already be achieved even at this initial stage of Sun‐to‐Earth modeling.
