Working in the rain, not storms, is a good opportunity for meeting new customers who are looking for a window cleaner because more w/c's stay at home at the first sight of rain or if the weatherman has predicted rain forecasts.
I pick up as many new customers on rainy days as I do on lovely blue sky days when the sun is low for the time of year.
It's about sticking to a work routine and not beating yourself up 'cause it's raining and "oh dear my customers won't like it", or rather, you haven't trained your customers that you work in inclement weather or are just too scared to risk losing the odd customer in order to fulfil a days earnings.
With the earnings I've gained from working in the rain, I set that aside to buy myself an Ionics gutter vac now. Now when it's raining I'll have the choice of either window cleaning or emptying out gutters (up to 30ft) without having to ensure the customer is home to plug into their electrics or run a separate generator to use a vacuum. Beats staying home losing a wage and getting bored watching childrens TV.