December in Porto Feliz, Brazil, brings average daily highs of 31°C and overnight lows of 20°C in the 2016–2025 historical record. Allow room to shorten long outdoor plans when the day's forecast is hotter than you want. A schedule with easy breaks and less travelling between stops will give you more choices.
In the record, at least 1 mm of rain or snow falls on 17 of 31 days on average, a daily chance of 54%. Give wet-weather alternatives a proper place in the itinerary. Arrange outdoor plans so you can move them between days, and pack a rain layer rather than relying on a completely dry run of weather.
The calculated day length, sunrise to sunset, averages about 14 hours. Sunshine averages 11 hours a day. The longer daylight window gives you more choice about when to be outside; it does not mean every part of the day will be sunny. Sunshine is a separate measure, and those hours need not arrive in one uninterrupted stretch.
For a culture-focused visit, group the places you want to see into manageable areas, with time between stops. Check each venue's opening dates before fixing the order.
January has an average daily high of 30°C, 1°C lower than December. Its historical rain-day chance is 65%, compared with 54% this month. If your dates are flexible, compare those trade-offs with the kind of days you want. Neither set of averages predicts the conditions of one particular holiday.