Two colloquial phrases from Costa Rica I recently learned from spanishpod101 are related to this:
Son pelitos de gato nada mas
Translates to: "It's just little cat hairs". Meaning it's only light rain/drizzle
San Pedro esta corriendo los muebles
Translates to "St Peter is moving the furniture around". Meaning there is a big storm.
Here is the link to the podcast:
http://www.spanishpod101.com/2008/06/10/regional-spanish-series-61-costa-rican-18-st-peters-moving-the-furniture/
Please note: I am not specifically intending to promote this website. If anyone feels it is not appropriate to link to sites like this, please let me know.