A pool makes a difference in Chiang Mai's hot season from March to May, and it does not have to cost much more. Five places on this site have one. The Greenery Landmark, by the Superhighway north of Nimman, has 35 to 38 m² units from 6,000 baht a month with the pool and gym free to use; it is not on booking sites. The Pacific Cool Chic, just north of the Old City moat, rents 32 m² rooms for 6,500 baht if you stay three months. Yantarasri at Nimman has 40 m² studios in a garden setting from 8,500 baht with a resort-style pool, coworking room and shared kitchen; pool use costs 500 baht a month. Smith Residence by Chiang Mai Gate has a rooftop pool and gym with views to Doi Suthep and 32 m² studios for 9,500 baht. The Cosy Huay Kaew charges 14,000 baht for 35 m² with kitchenette, pool, gym, parking and weekly cleaning; booking sites list it as closed for renovation, so call before you go. Three of these five are in or near Nimman and two in or near the Old City. Electricity is extra at all of them except where stated on the listing.
5 places, cheapest 6,000 ฿ a month. Show them on the map

Nimman · Serviced apartment · ✈ 62 dB
Serviced apartments by the Superhighway north of Nimman, with free pool and gym, free repairs and no common-ar…

Old City · Hotel · ✈ 46 dB
70-room hotel on Hussadhisawee Road just north of the moat, with pool and covered parking.…

Nimman · Serviced apartment · ✈ 61 dB
40 m² studios in a garden setting off Nimman Soi 6, with a resort-style pool, coworking room and shared kitche…

Old City · Serviced apartment · ✈ 39 dB
Apartment building by Chiang Mai Gate and the Wualai Saturday market, with a rooftop pool and gym looking at D…
Nimman · Apartment · ✈ 52 dB
35 m² rooms with kitchenette and mountain views off Huay Kaew Road. Weekly cleaning, water and parking include…
The Greenery Landmark, from 6,000 baht a month for a 35 m² unit with free pool and gym. The Pacific Cool Chic costs 6,500 baht but needs a three-month stay.
At The Greenery Landmark, Smith Residence and The Cosy Huay Kaew it is part of the building. Yantarasri at Nimman charges 500 baht a month for pool use.
Smith Residence by Chiang Mai Gate has a rooftop pool and gym, with 32 m² studios for 9,500 baht and 64 m² suites for 20,000 to 21,000 baht.