In Songkran Bangkok, the order of the day matters most. Put an early finisher in the morning, such as the Grand Palace (09:00 start, 11:00 end) or the Wat Saket tuk-tuk tour (meet 09:20, end 12:30), then join the Khao San or Silom splash zones after lunch. With daytime temperatures of 35 to 40 degrees, keep midday outdoor time short.
Once the heat eases in the afternoon, a walking tour fits. The Talat Noi walking tour runs 15:30 to 18:00 and the 15:30 slot of the Wat Pho and Wat Arun tour finishes at 18:00. Both are on foot, so leave large luggage at your hotel.
In the evening a tuk-tuk passes closest to the festival mood. The Wat Saket and Khao San Road tour meets at 17:30 and reaches Khao San around 19:30, and the Old Town night tour meets at 19:00 with a sticky noodle dish included. Tuk-tuks have no trunk and allow only a small backpack, so bring only things that can get wet.
Dress rules stay the same during the festival. The palace and temples require covered shoulders and knees, and Wat Pho and Wat Arun restrict crop tops, sleeveless tops and short shorts. Wear temple-appropriate clothes first and carry a spare change for after you get wet.
For a self-guided day, use an early palace or temple visit as your anchor, then leave time to join a festival zone. Check opening hours and carry only water-resistant essentials.