Sea temperature and swimming season in Bandar-e Deylam
The sea off Bandar-e Deylam is comfortable for swimming from April to December. It peaks at 34.1°C in August and drops to 16.4°C in January.
Month by month
Sea temperature, the air you climb out into, and the wind that decides how that feels.
| Month | Sea | Air | Wind | Feels | What to wear |
|---|---|---|---|---|---|
| January | 16.4°C | 18.7°C | 3.6 m/s | Bracing | 3/2 mm full suit |
| February | 16.9°C | 19.1°C | 3.4 m/s | Bracing | 3/2 mm full suit |
| March | 19.0°C | 24.3°C | 4.0 m/s | Bracing | shorty, or nothing if you are acclimatised |
| April | 23.1°C | 32.0°C | 3.5 m/s | Very comfortable | none, or a rash vest |
| May | 27.2°C | 38.1°C | 3.8 m/s | Bath-like | none needed |
| June | 30.1°C | 40.9°C | 5.1 m/s | Bath-like | none needed |
| July | 32.5°C | 41.7°C | 4.4 m/s | Bath-like | none needed |
| August | 34.1°C | 41.1°C | 3.2 m/s | Bath-like | none needed |
| September | 32.7°C | 39.2°C | 3.6 m/s | Bath-like | none needed |
| October | 28.9°C | 33.4°C | 3.2 m/s | Bath-like | none needed |
| November | 24.3°C | 25.9°C | 3.0 m/s | Very comfortable | none needed |
| December | 19.5°C | 20.9°C | 3.2 m/s | Comfortable | shorty, or nothing if you are acclimatised |
Air is the average daily maximum — roughly what you would meet swimming in the middle of the day. An arrow marks months where the air is colder than the sea.
When in the day can you swim?
Daylight and burn risk by month, in Asia/Tehran local time.
| Month | Sunrise | Sunset | Daylight | Peak UV |
|---|---|---|---|---|
| January | 07:06 | 17:31 | 10h 25m | 4.3 |
| February | 06:49 | 17:57 | 11h 08m | 6.1 |
| March | 06:19 | 18:17 | 11h 58m | 8.4 |
| April | 05:42 | 18:36 | 12h 54m | 10.5 |
| May | 05:15 | 18:55 | 13h 40m | 11.7 |
| June | 05:07 | 19:11 | 14h 04m | 12.3 |
| July | 05:18 | 19:12 | 13h 54m | 12.5 |
| August | 05:36 | 18:51 | 13h 14m | 12.1 |
| September | 05:53 | 18:15 | 12h 21m | 10.4 |
| October | 06:11 | 17:39 | 11h 28m | 7.7 |
| November | 06:34 | 17:13 | 10h 39m | 5.1 |
| December | 06:57 | 17:11 | 10h 13m | 3.9 |
Open water burns faster than a beach: the surface reflects sunlight up at you, and sunscreen washes off in the first few minutes. A long swim under a UV index above 6 needs a rash vest more than it needs more cream.
What the bands mean
| From | Description | In practice |
|---|---|---|
| above 26°C | Bath-like | Warm enough that it offers no cooling at all |
| above 22°C | Very comfortable | Swimwear, no time limit for most people |
| above 19°C | Comfortable | Pleasant once you are in; most people swim happily |
| above 16°C | Bracing | Swimmable but short; many prefer a shorty wetsuit |
| above 12°C | Cold | Wetsuit territory. Unprotected swims should be brief |
| below 12°C | Dangerous | Cold shock risk. Specialist gear and supervision |
Do you need a wetsuit in Bandar-e Deylam?
Some months, yes. The sea drops to 16.4°C in January. What thickness, month by month, for swimming and for surfing →
Other coastal cities in Iran
Where these numbers come from, and what they miss
- Open water, not your beach. The measurement is a satellite cell about 28 km across, centred 8.5 km from Bandar-e Deylam. Shallow bays and lagoons run warmer; exposed coasts with upwelling run colder, sometimes by several degrees.
- Surface temperature. Below a few metres the sea is often noticeably colder, and in summer a warm surface layer can sit over much colder water.
- A six-year average, not a thirty-year normal. Sea temperature varies little between years, so this is close — but it is not a climate normal, and any individual year will differ.
- Averages hide storms. A monthly mean says nothing about the week a cold current arrives.