How we measure

Every temperature, rain and sunshine figure on this site is computed by us from public daily data - not typed in from a brochure and not rounded up to sell a holiday. This page explains exactly what the numbers are, where they come from and where they can mislead you.

The period: 1991-2020

All averages cover 1 January 1991 to 31 December 2020, the current 30-year "climate normal" period defined by the World Meteorological Organization. Many travel sites still quote the 1961-1990 normals, which are about 0.5-1.0°C cooler than today's climate at most destinations. Averages are computed from every day in the period: a January figure is the mean of roughly 930 January days.

Daily land data

For each destination we take one representative point (a resort or town, named at the bottom of every page) and pull the daily maximum, minimum and mean temperature, precipitation, relative humidity, wind and cloud cover for all 1991-2020. Source: ERA5-Land reanalysis via Open-Meteo (0.1° grid, CC BY 4.0) for 274 destinations.

Limitation. Reanalysis data describes a grid cell (about 11 km across), not a thermometer on the beach. On coasts and small islands a cell is partly sea, which can damp daytime highs by 1-2°C compared with a station in the resort; in valleys and on mountainsides it can miss local extremes. Where two resorts sit in the same cell their figures are identical, and we say so on the page instead of pretending otherwise.

Sea temperature

Monthly sea surface temperature comes from NOAA Coral Reef Watch's 5 km satellite product (public domain). For each destination we use the nearest sea cell within about 30 km of the representative point and average the monthly values over 1991-2020; 249 of 274 destinations have a sea figure. Inland destinations show no sea temperature rather than a guess. "Warm enough to swim" means a monthly average of 22°C or more; 18-22°C we call bracing.

Sunshine hours

Sunshine hours are estimated as daylight hours × (1 − average cloud cover) from the same daily reanalysis, and every page labels them as an estimate. We checked this against published station normals for 14 destinations: the estimate is typically within about 1 hour a day, whereas the reanalysis's own "sunshine duration" variable overstates sunshine in cloudier places by 2-5 hours (it counts any direct sun above 120 W/m²), so we do not use it. Daylight hours, sunrise and sunset are calculated astronomically for the 15th of each month in local time, including daylight saving as of 2020.

Definitions

• Daytime high / night-time low: mean of the daily maximum / minimum temperature over the month.
• Hot: average daytime high of 25°C or more. Warm: 20-25°C. Mild: 15-20°C. Cool: under 15°C.
• Days over 25°C: share of days in the month whose maximum reached 25°C (likewise 30°C).
• Rainy day: a day with 1 mm or more of precipitation. Monthly rainfall is the mean of the 30 monthly totals.
• Wettest / driest year: the calendar year with the highest / lowest total for that month within 1991-2020.
• Record high / low: the single hottest daily maximum and coldest daily minimum for that month within 1991-2020 in the source data - not official station records.
• Warmest 10% of days: the 90th percentile of daily maxima; coldest 10% of nights: the 10th percentile of daily minima.
• Compared with London: difference in average daytime high against our London data point for the same month.
• Flight time: an estimate for a direct flight from London Gatwick, 45 minutes plus great-circle distance at 800 km/h. Real schedules vary; connections are not included. Short-haul is up to 4.5 h, mid-haul 4.5-7 h, long-haul over 7 h.
• Best months: a simple score - half for daytime highs in the 24-32°C window, 30% for few rainy days, 20% for sunshine hours. It favours beach weather; city-break lovers may prefer cooler months.
• Country pages: the mean of the destinations we track in that country, so they reflect resort areas rather than the whole territory.

What we track

274 destinations in 60 countries, chosen because UK travellers search for their weather. 119 of them have month-by-month detail pages; the rest have a 12-month overview. Place coordinates and names come from GeoNames (CC BY 4.0), airports from OurAirports (public domain).

Corrections

If a figure looks wrong - a point placed on the wrong side of a mountain, a resort mapped to the wrong town - tell us. We would rather fix the data than argue with it.