What's a typical rainy day like in Costa Rica's rainy season (early October)?

Lots of good answers about the weather have already been posted. Basically, you should expect showers in the afternoons. As far as driving, it's absolutely worth it to get the GPS system since roads are poorly marked and addresses are not standardized. I don't think you'll really need 4-wheel drive for the trip from San Jose to Arenal and Arenal to Guanacaste. You're going to have a great time!

It depends on where you're going. I lived in Costa Rica for two years. Usually the rain would come in during the afternoon. Anywhere from a short shower and sunny afterwards, to the downpour of your life, sometimes lasting the rest of the day. Usually afternoon, though. In all the times I've been to Guanacaste, it's never rained while I was there, but I know it must rain sometime. It's horribly hot too, by the way. Not humid like the Caribbean side, but downright hot. Good luck on the car rental thing. Most tourists are okay, though I'd never drive in Costa Rica. The drivers are wild. Just be very careful, and watch out for potholes & stuff, that are not clearly marked. Also, beware of driving in the rain in any mountainous area..they have a lot of mudslides. Keep your belongs locked up, and out of sight. Have a great trip!

I live in Costa Rica and you should expect some rain in the afternoon most of the time. Bu some days we have rain early morning but not that often, so I would recommend you to wake up early and do the driving early morning because it will be hard to drive from one place to another with rain. If you are heading just to Arenal and Guanacaste you shouldn't have a problem with a regular car roads are bad but not terrible Have a nice time while you are in Costa Rica

Where are you going? That is important both for your selection of car and for the weather you will encounter. The rainy season is more a Pacific coast and mountain thing and the Caribbean coast is the same or slightly drier (lot of rain but lots of stretches of sun). In the mountains it will probably rain afternoons and evenings (unless you are plain unlucky) and you should get some time to get out between rains on the Pacific coast (unless unlucky). If you are going to Monteverde or anywhere without a paved road you will need a 4 wheel drive for the clearance but otherwise you should be fine.

Central Valley of Costa Rica is where the main centres of population are located, the average temperature is 22°C (72°F) and the country has a spring-like climate year round. In the coastal areas, the temperature is much hotter and humid, while the Pacific Northwest can be extremely hot and dry. The rainy season starts in May and finishes in November, although there are distinct regional variations. June and July are the wettest months, particularly on the Caribbean side, but the season can run from May until December. The 'warm' dry season is December to May, though temperature differences between summer and winter are slight. March is the height of the dry season, and the humidity is lower at this time, making this a popular time for visitors. Arenal volcano is some times hard to see due to the clouds, but the best time of year to give it a shot is April and May. Wilson Rojas www.interviajescostarica.com