Swedish: Det finns inget dåligt väder, bara dåliga kläder
Norwegian: Det finnes ikke dårlig vær, bare dårlige klær
Meaning: "There's no bad weather just bad clothing."
What he said about being ready to layer for cold. We had a full day of snow in Yellowstone last month (June), which was still in the Continental US. Glacier National Park was largely still closed, as were parts of Mt. Rainier. The following was just a few weeks ago in the Northwet, while home in Maryland was sweltering in heat:
Just about any cheap gear will fall apart with the heavy wear of daily use on a bike in the rain.
Be prepared for 40 degree rain every day for the entire trip and be happy when it doesn't happen.
More than 3 shirts/pants/etc is too much.
Stop early enough to set up while it's light for a number of reasons.
There's no such thing as "an extra tarp" or rain fly.
Have a way to charge all the devices we normally carry these days.
Get up early enough that you don't cumulatively snooze away days of vacation time.
Look at your tread, tire pressure, brake pads, and chain (if the bike has one) every morning before starting out.
I always have extra food and water, in case a last grocery opportunity just isn't where I'd hoped for.