About This Data
This page projects each capital's weather forward to 2030, 2040 and 2050 using straightforward statistics run on real, measured data. For each variable, one trend line is fitted to the full 50 year daily record used elsewhere on this site, then carried forward. Around that line sits a Best and Worst scenario, a statistical range built from how much the historical yearly values actually wobble around the trend. A narrow range means the trend has held steady for 50 years. A wide range means the yearly numbers bounce around a lot, so the future is genuinely less certain, not a promise of exactly what year 2050 will bring.
What this projection actually is
INZIU has something valuable: nearly two hundred capitals' worth of real daily weather measurements going back decades. That record is enough to ask an honest, focused question: if the pattern already on file keeps going, where does it point next? Real climate projections, the kind behind IPCC reports, run physical simulations across dozens of institutions and emissions pathways. This page doesn't do that, and presenting a simple trend line as if it were one of those simulations would overstate what it actually shows.
The trend and its range
Each chart shows one bold line, the full record trend, fanning out from today toward 2050. Two fainter dashed lines sit above and below it: Best and Worst scenarios, set 95% apart based on the trend's own statistical uncertainty. Temperature, tropical days and frost days label the warmer end Worst and the cooler end Best. Precipitation and sunshine hours get a Low and a High estimate instead, since more or less rain, or more or less sun, isn't universally better or worse. An R² value next to the trend shows how tightly the full record's yearly values actually sit on a straight line. A lower R² means more year to year noise, so read the projection as directional rather than exact.
What's projected
Five variables per capital: annual average temperature, tropical days above 30°C, frost days below 0°C, total annual precipitation, and total annual sunshine hours. The first four are the same headline figures Climate Capitals already tracks historically, carried one step further into a trend based future. Sunshine hours is new to this page, built from the same daily record Meteo Capital Cities already shows day by day.
