regardless of the weather or circumstances; in any event:
The concert will be held, rain or shine. He's always a reliable friend, rain or shine.
Examples from the web for rain or shine
Every morning they would exercise the horses, rain or shine.
He did this rain or shine but especially during rain and early morning winter darkness.
Walks typically occur two or three times a day, rain or shine, and require no reservations.
Most of the market is covered and open rain or shine.
And, since the race runs rain or shine, be prepared for whatever the weather brings.
City concerts at the amphitheater are held rain or shine.
Walks return to original starting point and are rain or shine.
Programs are given rain or shine, so be prepared with an umbrella or rain coat if skies look forbidding.
The tour lasts approximately one hour and take place rain or shine.
Workshops held rain or shine and are non-refundable.
Idioms and Phrases with rain or shine
rain or shine
No matter what the circumstances, as in We promised we would finish the project tomorrow, rain or shine. This term, first recorded in 1905, still refers to weather, as well as other uncertainty, and always implies that an activity will be carried out, no matter what. For a synonym, see hell or high water