My umbrella!

For the past 2 days i have been carrying around my heavy umbrella, and no rain!or it has rained but only when i have been stuck inside the office.
So today before heading out i asked my mum what she thought, she said DON'T bring it, it won't rain and it's heavy to carry.
And therefore i listened to her advice, but guess what...i set my foot outside and it starts to rain.
So here I'm without an umbrella!

Why?why?why?