Yes, there are multiple flights from Bangkok Intl to Trieste for under ฿ 23,960. The cheapest flight booked recently is on Etihad Airways for just ฿ 21,534, but on average you can expect to pay ฿ 25,727.
There are no direct flights from Bangkok Intl to Trieste, but Cheapflights can provide you with all the information you need to find the fastest route with the fewest stops.
In Bangkok Intl, there will be less rainfall in Bangkok Intl compared to Trieste over the next 3 days.
You can imagine temperatures to be in the 36 °C range in April. The weather in Trieste is generally colder than Bangkok Intl's. As flight availability is subject to become more limited as peak season approaches it is ideal to book in a timely manner.
There are many flights that can get you from Bangkok Intl to Trieste in 19h. Fly via Etihad Airways or เอธิโอเปียแอร์ to get the fastest option. This flight may include one or multiple stops.
Flying on Etihad Airways is currently your cheapest option to Trieste, with prices starting at ฿ 21,535. Another option worth looking into is เอธิโอเปียแอร์, starting at ฿ 29,891 return.