About Where's Hot When
Curated by Hugo. Updated 23 September 2026.
What this is
A climate reference for people choosing when and where to travel. Pick a month, read the colour, open a place. The map answers two questions plainly: where it is warm in a given month, and where it is cool enough to escape a heatwave in the same month. Both are usually treated as taste. They are data.
It is not a forecast. It compares monthly daytime-high means, average rain days and observed variability across the historical record. It cannot tell you whether it rains on the Tuesday you land. That distinction is the whole point.
The interactive map is the primary surface; the month guides are the long-form companion.
How the data works
Every colour on the map is a long-run monthly mean of daily maximum temperature, computed per point from ten years of dailies (2016 to 2025, 10 full years). The underlying source is the Visual Crossing global historical archive, which blends physical station observations from the NOAA Integrated Surface Database and national met services with reanalysis fill where stations are sparse. Millions of daily rows are aggregated into twelve monthly means per point.
The dataset carries 15,498 measured points. The map turns those measurements into a continuous land-only dot grid, using interpolation between nearby measured points. Named destinations and interpolated grid cells are different things: a grid cell helps the map read continuously, while destination facts come from a measured source point.
The signature stat is daily-high spread: the width between the 10th and 90th percentiles of daily maxima across all ten years for the chosen month. For example, hypothetical endpoints of 24° and 32° produce an 8° width. Averages hide the shape of a month; the width shows how much daytime highs varied.
The 2025 lens shows monthly means from that observed year. The ten-year lens is the historical climate reference. Live Now is separate again: it shows a fresh current reading when one is available. None of these lenses is a forecast, and missing or stale readings are shown as unavailable rather than estimated.
Year-to-year reliability. The destination summary counts how many covered years had a monthly mean daytime high within 2°C of that month's historical average. The Reliable filter requires this in at least 80% of covered years, with a minimum of eight years. Each year-month must have observations for at least 90% of its calendar days. A count such as 9 of 10 describes the 2016 to 2025 record. It is not a 90% forecast probability for a future holiday.
Warm and mostly dry. The expanded explanation also counts years when at least 70% of observed days had a daytime high of 24 to 30°C and less than 1 mm of rain. Both temperature and rainfall must be present for at least 90% of the month. This is a fixed, explained example of holiday conditions, not a prediction or a personalised score.
Daily variability. The daily high spread is the width between the 10th and 90th percentiles. It describes variation between days, separately from year-to-year consistency. A width is not a plus/minus range. Older daily-variability grades use widths below 6°C, below 9°C, below 13°C and 13°C or more, respectively.
Beach mode restricts the map to points whose active reading sits in the warm bands (19 to 25, 26 to 32, 33+). Under the ten-year and 2025 lenses the monthly mean decides; under the Now lens the current reading does. Cold coasts are muted rather than hidden, since geography alone is not the answer.
Who makes it
Editor's note
I built this because the "best places to visit in March" lists were all the same twelve cities in a different order, and none of them told me what the weather would actually feel like on the ground. So I made the tool I wanted, in the spirit of seat61.com: one person, an obsessive dataset, plain prose, no upsell.
The work is unglamorous. Ten years of dailies, cleaned per point, aggregated twelve ways, coloured so a continent reads at a glance. Then the writing, one month at a time, one honest paragraph per place. Where I have an opinion I say so and sign it. Where the data is thin I say that too.
If a page here saves you from a rainy week you did not want, it has done its job.
Hugo
Sources
Weather. Daily observations and reanalysis via the Visual Crossing global historical archive, itself sourced from the NOAA Integrated Surface Database, national meteorological services, and ERA5 reanalysis where stations are sparse.
Coffee and beer estimates. Country estimates cover 193 countries and scale US anchor prices using country price levels. A set of 56 editorial destination estimates accounts for selected city and resort differences. These are not surveyed local prices. Beer means 500 ml draught; figures and exchange rates are a July 2026 snapshot. The card labels all prices approximate. The scaling reference is the World Bank price-level indicator.
Cost of living. Coffee and beer anchor prices scaled by the World Bank price-level indicator (nominal GDP per capita divided by PPP GDP per capita, US = 1.0).
Flight footprint. Return economy kg CO2e from London Heathrow using DEFRA 2024 conversion factors with radiative forcing (0.15298 kg per pkm below 3,700 km, 0.19085 kg above). Great-circle distance underestimates real routing by 8 to 12%, so treat the number as a floor.
Travel advisories. Curated snapshots of the UK Foreign, Commonwealth and Development Office country pages. Each chip links to the live FCDO page; check the latest advice before booking.
Tap water. Curated from the CDC Yellow Book and WHO guidance, reduced to safe, mixed, unsafe.
Place descriptions. Editorial where written; otherwise the Wikipedia REST summary resolved by geosearch, attributed inline under CC BY-SA.
Live Now. Current temperatures are shown separately from monthly daytime highs. A refresh job is scheduled every three hours and processes a bounded batch; coverage and fetch times vary by place. Readings over six hours old, missing readings and paused feeds are unavailable. Grey dots in Now mode have no fresh reading. A current temperature is not directly comparable with a monthly average daytime high, so we do not call that difference a weather anomaly.
Data terms
The computed statistics on this site (monthly means, swing percentiles, rain days, steadiness bands, the 2025 lens) are viewable and citable with attribution to wheres-hot-when.com. Quote a figure, screenshot a map, link back. That is the ask.
The underlying daily observations are licensed from Visual Crossing and are not redistributed here. If you need the raw dailies for your own work, buy them from the source. Nothing on this page grants an open licence to the underlying archive.