Cartagena de Indias has an average temperature of 27.7ºC, which sounds wonderful for most north Europeans and the majority of Americans but with levels of up to 82% humidity the number can be a little misleading.
There are two distinct seasons, the dry season and the rainy season that you should be aware of when deciding when best to travel.
The Dry Season
The coolest time of year is between December and April when the
Trade Winds knock a couple of degrees centigrade off the average
temperature and reduce the humidity levels notably. During these
four months it rarely rains, making it the most popular time of
year for visitors from the interior of the country.
In the same way as Spring lifts the spirits in North Europe, the
arrival of the first breezes in the city in December bring a smile
to the locals' faces by drawing a line under the rainy season.
The Rainy Season
The rains officially start in April and stretch to November
although it doesn't rain all the time. Precipitation is heaviest in
the months of August, September and October when tropical downpours
are more frequent, on average every other day in September and
October.
Of the eight months of the rainy season, May and July are considered a mini-summer coinciding with the holidays for schools and universities.
Unlike the dreariest months in Europe and the US, even on
Cartagena's rainiest days the sun is normally likely to come out at
some point. Locals use the rain as an opportunity to catch up on
some sleep.
Humidity
Humidity levels during the rainy season average just over 80% and
there are days in September and October in the build-up to a
downpour when it will feel like you are stuck in a pressure cooker
so bring an abundance of T-shirts to change into.