jsmc
i wouldnt think about another income , i dont know your personal circumstances, but any time i have thought about it , and one time i did it, i found they both made it hard to concentrate on either one without neglecting one seriously
If i was you i would look seriously , and honestly at your working habits, hours, prices, method etc
And determine what you could do better to make more through the good times, and save for bad
Also maybe look at cutting overheads for business, and maybe personal!
I cant see that window cleaning cant pay even for losing a bit of time through bad weather