There are a few ways you can look at crap weather.
You can look out the window, see its raining and say, "no, i wont go out, weather is abit crap. Ill go out tomorrow"
But, ofcourse, its raining the next day, so you dont go out then aswell.
Or, you can think to yourself, "**** it, im going out" and actually go out. Its never too bad when you get out. And, the weather here being not the best, means you cant sit in waiting for warm sunny days. Just get out! Put a water proof on(or if its warm enough, i just have a jersey and a base layer, and have a thin cape thing to put on if i start to get cold) and go out.
But, heres the thing to remember.
Dont really force yourself to go out. If you really dont feel like it, and you've been out over the past few days, dont go out.
Last year i would force myself out in crap weather, when i didnt want to.
This year, i look at how much ive already trained that week/previous week and what im going to be doing over the next week and think, nah ill stay in and relax(thats if ive already done abit, or if i really dont feel like going out)
Im much faster this year then what i am last year.
But, on some rainy days, you cant just sit in and hope it goes away, you have got to go out.
On sunday i didnt go out though. It was raining pretty heavy, and would have been misserable if i had gone out. I stayed inside instead and relaxed/caught up on sleep.
Just my take on it all mind, going by how my training is this year(with not going out as much, and having more fun on my bike) compared to last year(going out too many days, and forcing myself out)