Aug 08 2011

Our Climate in Costa Rica

As you probably already know, there are two seasons in Costa Rica, a wet season (winter) from May to November, and a dry season (summer) from December to April.  Additionally, there are many micro-climates here that change the weather, usually depending on altitude and topography.  The climate is different on the Caribbean slope than on the Pacific side.  Guanacaste in the northwest region of the country gets a little less rain and more sun, while the Osa Peninsula in the southwest gets more rain and less sun.

But today I want to focus on our weather right here in San Ramon.  We live in the mountains at 4,000 ft. elevation, while the town of San Ramon (4 miles away) is about 3,450 ft.  It’s July and we are in the middle of the rainy season.  Yesterday, we had a downpour and for the last several days it’s been raining pretty hard.  The San Ramon area gets between 60 and 80 inches of rain a year.  But interestingly, only 15 days of the rainy season provide 70% of the total annual rainfall and yesterday was one of those days. Even though, we’ve had a fairly dry rainy season so far.

May, which usually has nine inches of rain, had about four.  June, which usually has more than 11 inches, had about 6 inches of rain.  July is still an open book, but averages 8.5 inches.  The wettest months, September and October, are yet to come.  Because weather data is not available for San Ramon, I had to go with San Jose data.  As you can see from the colored chart above, it’s similar, between 60 and 80 inches per year. Since we live in the mountains at 4,000 ft. near San Ramon, you can probably tack on an inch or two to some months.

Since 70% of the annual rain falls on only 15 days of the year, those days must average 3.73 inches, times 15 days, or 56 inches of rain.  The rest of the time, the other 180 days of the rainy season, receives about 24 inches.  Most days in the rainy season are not downpours, but rather rainy days somewhat like Seattle, Washington or Portland, Oregon, with a lot of clouds, a little rain, drizzle, showers, and brief periods of hard rain. 

San Ramon is noted for its pelo de gato (hair of the cat) which translates into soft drizzle, so typically it doesn’t rain that much most days – but it seems like it’s always raining, especially in the afternoons. Usually weather-talk is small-talk but for me, an amateur meteorologist, it’s exciting and a prime topic of conversation. Every morning at 6:00 am, I rush out to look at my mercury thermometer and rain gauge. Gosh, life is so exciting! As Gloria always tells me, I’m easily pleased.

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