Methodology & data sources
Where our numbers come from, how we calculate them and what they cannot tell you.
Last updated:
Data sources
| Measure | Source | Period | Licence |
|---|---|---|---|
| Day and night air temperature | Open-Meteo Historical Weather API (ERA5 reanalysis) | 2016–2025 | CC BY 4.0 |
| Sea surface temperature | Open-Meteo Marine API | 2023–2025 | CC BY 4.0 |
| Rainfall | NASA POWER climatology (MERRA-2) | 2001–2020 | Public domain |
| Maps and places | OpenStreetMap contributors, map tiles by OpenFreeMap | Updated continuously | ODbL 1.0 |
The climate figures were last calculated on for 20 destinations.
How the numbers are calculated
- Day and night temperature is the average of each day's highest and lowest air temperature in that calendar month, over ten years. One point is used per destination, close to its main resort area.
- Sea temperature is the average daily sea surface temperature at a point just off the coast. Sea data is only available from 2023, so it covers three years.
- Rainfall is the average total rainfall for the month, in millimetres.
- All values are rounded to whole numbers. Fahrenheit values are converted from Celsius.
What “beach weather” means
We mark a destination as having beach weather in a month when all three are true:
- the average day temperature is at least 25°C (77°F),
- the average sea temperature is at least 24°C (75°F), and
- average rainfall for the month is 80 mm or less.
It is a simple rule of thumb, not a guarantee. A month can pass the test and still have a few rainy or windy days.
Limitations
- Model data, not weather stations. ERA5 and MERRA-2 are reanalysis models. They combine observations into a grid that is tens of kilometres wide, so mountains, microclimates and the difference between one side of an island and the other are smoothed out.
- Averages hide extremes. A month with a 28°C average can still have cool spells, storms or heatwaves.
- What we leave out. We tested rainy-day counts and sunshine hours but do not show them: in this data both were clearly higher than official station records, especially in the tropics.
- Distances on our maps are straight-line distances (“as the crow flies”). Walking or driving distances are longer.
Updates and corrections
Climate averages change slowly, so we recalculate them once a year. Place and map data from OpenStreetMap is refreshed more often. If you spot an error, please let us know – see the About page for contact details. Vacay Maniac is produced by RJ Digital.