NASA's MEERA-2 climate model predicts when the air up there is cold enough:

Credit: SDO/AIAĬolorful Type II polar stratospheric clouds (PSC) form when the temperature in the stratosphere drops to a staggeringly low -85C. Solar wind flowing from this coronal hole should reach Earth on Jan 1, 2024. Switch to: Europe, USA, New Zealand, Antarctica Neutron counts from the University of Oulu's Sodankyla Geophysical Observatory show that cosmic rays reaching Earth are slowly declining-a result of the yin-yang relationship between the solar cycle and cosmic rays. Credit: SDO/HMIĬosmic Rays Solar Cycle 25 is intensifying, and this is reflected in the number of cosmic rays entering Earth's atmosphere. All of these sunspots have stable magnetic fields that pose no threat for strong solar flares.