BR Tropical Hot and Cold Months Calculator

Tropical Hot and Cold Day Counting (Brazil)

Brazilian climatology calls a day hot once the maximum hits T_max ≥ 30 °C, and cold when the minimum slips to T_min ≤ 15 °C. Tally those days month by month and you get the climatological calendar that growers, the tourism trade and power planners all lean on. Watch the yearly totals shift with ENSO phases, with Atlantic SST anomalies, and with the heat that cities trap.

For INMET, a heat wave means three or more days in a row where T_max clears the 90th percentile of the station's 1991–2020 climatology, which follows WMO guidance. ABNT NBR 15220 carves Brazil into eight bioclimatic zones. How many hot or cold days a zone sees feeds straight into wall thickness, glazing and ventilation calls for buildings that rely on natural conditioning.

Applications

Sizing HVAC for a school or hospital. Checking whether a passive design strategy holds up. Building an agricultural calendar (chilling hours for stone fruits, heat stress on cattle). Pricing parametric weather insurance. Gauging the public-health risk that comes with temperature extremes.

FAQ

Why 30 °C and 15 °C as thresholds? These are the working limits INMET and several state agencies use to flag thermal discomfort in a tropical climate. Push past 30 °C and cooling demand jumps; drop below 15 °C and heating starts to matter in the South and Southeast.

How does it differ from a heat-wave count? A heat wave has to satisfy a consecutive-day rule and a relative threshold (the 90th percentile of the local climate). The hot-day count just checks each day against a fixed absolute limit, with no dependence between days.

Do monthly means work for this metric? Only as a rough stand-in. The official count needs daily T_max/T_min from automatic or conventional stations, because a monthly average buries the extremes that actually drive the tally.