Rio sunset time, month by month on the bay

Summer gives the longest evenings. The sun sets at about 6:44 PM on 15 January and at about 6:32 PM a month later, in mid-February.^1,10 By mid-March the time has moved to about 6:08 PM, and by mid-April it is about 5:39 PM.^5,11 Autumn shortens the evenings quickly here, and a traveler who visits in April will notice dusk arriving noticeably earlier than in the postcards of summer evenings on the beach.

The early dusks belong to late autumn and winter. Sunset comes at about 5:19 PM in mid-May and about 5:15 PM in mid-June, the earliest of the year.^6,2 Curiously, the solstice is not the earliest evening: on 21 June the sun sets at about 5:16 PM, a minute later than on 15 June.^7,2 From July the evenings stretch again, with sunset at about 5:24 PM in mid-July and about 5:37 PM in mid-August.^12,13

Spring brings the light back step by step. The sun sets at about 5:47 PM in mid-September, about 5:57 PM in mid-October and about 6:14 PM in mid-November.^8,14,15 In mid-December it is back to about 6:34 PM, and on 21 December, the summer solstice in Rio, it sets at about 6:37 PM.^16,9 Put together, the sunset time in Rio de Janeiro moves through a wide band during the year, which is why one month's advice rarely fits another.

Sunset is not the end of the show. Civil twilight, the stretch when the sky stays bright enough to see without lights, runs until about 7:08 PM in mid-January, about 24 minutes after the sun goes down.⁴ In mid-June it ends at about 5:40 PM.²⁰ This is the time of the deepest colors over the water, when the mountains turn to silhouettes and the streetlights of Flamengo and Botafogo start to glow along the shore.

Twilight in the tropics is short compared with high latitudes, so the afterglow does not linger the way it does in northern summers. Expect the sky to move from gold to pink to deep blue in well under an hour. Photographers should have their settings ready before the sun touches the hills: once the sun has gone, the window for bright, colorful shots of the skyline closes faster than you might expect.

Keep an eye on the sky above you as well as the horizon. ICMBio, the federal conservation agency, says the frigatebirds of the Cagarras islands hunt over Guanabara Bay and return to their nests at dusk.²⁵ On a clear evening their long, angular wings make striking shapes against the fading light, as they head back out to sea.

Rio's weather decides how much color you get. Summer storms in Rio tend to be brief but intense and to break in the afternoon, according to Alerta Rio, the municipal weather service.²⁴ Its review of a recent summer describes hot days with clear skies giving way to downpours later in the day.¹⁷ A storm that clears before sunset can leave dramatic, glowing skies over the whole bay, while one that arrives late can end the color early.

Autumn is a season of transition in the city's records. Showers still fall, but less often than in summer, and the number of cold fronts rises toward June.^27,19 Morning mist and fog also become more common in autumn, which rarely affects an evening sail but can make a dawn view hazy.¹⁸ A front can bring grey skies and wind for a few days, so a flexible date is worth more than a perfect forecast.

Riotur, the city's tourism authority, labels June to September as the dry months, cooler and with little rainfall.²¹ For a sunset sail that often means cleaner horizons and earlier evenings. From December to March it describes wetter, more humid weather with regular rain.²⁸ Neither season rules out a good sunset, but each asks for a different plan: in summer leave room for a shower, in winter book an earlier slot.