Thailand has a tropical climate with three distinct seasons: hot (March through May with average temperature in the upper 90s°F / upper 30s°C), rainy (June through October with the temperature averaging in the 80s°F / upper 20s°C) and cool (November through February with average temperature in the 70s or low 80s°F / low 20s to high 20s°C). In the north, during cool season, temperatures can be as low as the 40s°F / 5-10°C during the day. The southern part of the country has intermittent showers year-round.
Be very careful when walking in the sun or sun-bathing. Wear a hat plus a sun-block of at least SPF 15 and drink water or fluids regularly.