Your April weather guide
MildWeather in Istanbul in April
April is a reasonable time for Istanbul if you want a mild city break rather than warm-weather lounging. Average daytime highs are around 15°C, nights fall to around 9°C, and about 8 days have rain. That suits walking with layers and a waterproof, but not packing as though summer has arrived. For a UK traveller, the appeal is time outdoors without much heat; the catch is cool evenings and the need for flexible plans.
Long-term climate averages for Istanbul, not a forecast · 1991-2020
Istanbul, month by month
Your snapshot
At a glance
The useful details for Istanbul.
- Average daytime high
- 15.1°C
- 9 in 10 days stay below 20°C
- Average night-time low
- 8.8°C
- coldest 10% of nights: 6°C or lower
- Compared with London
- +1.6°C
- London averages 13.5°C in April
- Sea temperature
- 10.2°C
- year to year: 9°C to 11°C
- Sunshine per day (est.)
- 6.2h
- 47% of 13.1 h of daylight
- Rainy days (1 mm+)
- 8
- 47 mm over the month
- Humidity
- 76%
- Days over 25°C
- 0%
- none over 30°C
- Record high 1991-2020
- 26.8°C
- 2018-04-26
- Record low 1991-2020
- 1.5°C
- 2005-04-04
- Flight from London
- ≈ 3 h 54 min
- 2491 km, short-haul (estimate for a direct flight)
Records are observed extremes within 1991-2020, not typical holiday conditions. Warm-day percentages are shares of days, not day counts.
How April compares
April is the 7th warmest month of the year in Istanbul and ranks 129th of 134 destinations we compare for April - see where else is hot in April. Within Turkey it is 17th of 18 (Turkey in April). Against London's average high of 13.5°C in April, Istanbul is 1.6°C warmer by day and 3.7°C warmer at night.
Daytime and night-time in April
The typical April day in Istanbul peaks at 15.1°C, but that is an average: the warmest 10% of days reach 19.6°C or more. Roughly 1 in 333 days top 25°C. Nights average 8.8°C; one night in ten drops to 5.6°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest April day here reached 26.8°C (2018-04-26) and the coldest night 1.5°C (2005-04-04).
Rain in April
Wet (more than 8 rainy days): about 8 days with 1 mm or more, 47 mm in total. Year to year it varies a lot - the wettest April was 1991 with 127 mm, the driest 1999 with 14 mm. Humidity averages 76%.
Sea temperature in April
The sea averages 10.2°C - too cold for most (under 18°c). Depending on the year it ranges from 8.9°C to 11.3°C. For the warmest sea here, come in August (24.4°C).
Sunshine and daylight
Around 6.2 hours of sunshine a day (estimated from cloud cover), 13.1 hours of daylight: the sun rises about 06:25 and sets about 19:44 local time in mid-April. Average cloud cover is 53%.
Is April a good time to visit Istanbul?
April is not the strongest month here: mild days and frequent rain. The best months for Istanbul on our scoring are August, July, June; months averaging 25°C or more: Jul, Aug.
Mild days, cool evenings
April's daytime temperatures suit exploring on foot if you prefer mild conditions to heat. Warmer days can reach around 20°C, but that is the warmer end of the month, not the everyday expectation. Bring tops you can layer, a jumper and a jacket rather than relying on light clothing alone. Evenings need more thought: the average low is around 9°C, while the coldest nights can fall to around 6°C or below. If you plan to sit outside after dark, keep a warm layer with you. Choose April for manageable daytime temperatures, not for reliably warm outdoor evenings.
Leave room for rain in your plans
Rain is a meaningful part of the April trade-off, with about 8 rainy days during the month. A waterproof jacket and shoes you are comfortable wearing in wet conditions are sensible packing choices. Keep your outdoor plans flexible so you can move them around the forecast rather than committing everything in advance. There is still useful light for a city break: about 6.2 hours of sunshine within 13.1 hours of daylight gives you scope to spend time outside, without implying clear skies all day. The sea averages just 10.2°C, so treat this as a walking holiday rather than a swimming trip.
A little perspective
Istanbul through the year
April is highlighted. See how it compares with the rest of the year.
| Month | Day | Night | Sea | Sun/day | Rain mm | Rainy days | Days 25°C+ |
|---|---|---|---|---|---|---|---|
| January | 8.2°C | 4.1°C | 8.4°C | 3.1 | 85 | 12 | 0% |
| February | 8.8°C | 4.1°C | 7.3°C | 3.7 | 71 | 11 | 0% |
| March | 11.0°C | 5.6°C | 7.8°C | 4.8 | 72 | 11 | 0% |
| AprilSelected | 15.1°C | 8.8°C | 10.2°C | 6.2 | 47 | 8 | 0% |
| May | 20.0°C | 13.6°C | 15.4°C | 7.8 | 36 | 6 | 6% |
| Junebest | 24.9°C | 18.4°C | 20.8°C | 10.4 | 35 | 6 | 50% |
| Julybest | 27.6°C | 21.1°C | 23.5°C | 11.8 | 19 | 4 | 88% |
| Augustbest | 27.9°C | 21.8°C | 24.4°C | 10.8 | 20 | 3 | 91% |
| September | 24.1°C | 18.5°C | 22.5°C | 8.2 | 45 | 6 | 42% |
| October | 19.2°C | 14.5°C | 18.9°C | 5.3 | 78 | 9 | 4% |
| November | 14.4°C | 10.0°C | 14.8°C | 3.9 | 72 | 10 | 0% |
| December | 10.2°C | 6.3°C | 11.1°C | 3.0 | 97 | 13 | 0% |
Day = average daytime high, night = average night-time low, 1991-2020.Sun is hours per day; rainy days count 1 mm or more.
Day, night and sea
Monthly average temperatures, 1991-2020
- Day
- Night
- Sea
Best months here
On warmth, low rainfall and sunshine, start with these.
Keep exploring
Similar in April
Closest matches on daytime temperature, sea temperature and sunshine, in other countries.
Bulgaria · 15°C by day · sea 9°C
Sunny Beach
Czechia · 15°C by day
Prague
France · 15°C by day
Paris
Poland · 14°C by day
Krakow
United States · 15°C by day · sea 8°C
New York
A little more detail
Istanbul in April FAQs
Plain answers, grounded in the averages.
Is Istanbul hot in April?
Istanbul is mild in April: the average daytime high is 15.1°C and nights average 8.8°C. Roughly 1 in 333 April days reach 25°C.
Can you swim in the sea in Istanbul in April?
The sea around Istanbul averages 10.2°C in April, which is cold for swimming without a wetsuit. Between 1991 and 2020 it ranged from 9°C to 11°C depending on the year.
How much does it rain in Istanbul in April?
Istanbul sees about 8 rainy days (1 mm or more) and 47 mm of rain in a typical April. The wettest April between 1991 and 2020 was 1991 (127 mm) and the driest was 1999 (14 mm).
How sunny is Istanbul in April?
Istanbul gets around 6.2 hours of sunshine a day in April out of 13.1 hours of daylight (estimated from average cloud cover).
How does Istanbul compare with the UK in April?
Istanbul is on average 1.6°C warmer than London by day in April (15.1°C against 13.5°C).
What is the hottest April on record in Istanbul?
Between 1991 and 2020 the hottest April day in Istanbul reached 26.8°C on 2018-04-26, and the coldest night dropped to 1.5°C on 2005-04-04.
Is Istanbul much warmer than London in April?
Not much. Istanbul's average daytime high is 15.1°C, compared with 13.5°C in London, a difference of 1.6°C. That is a modest improvement rather than a change of season, so you will still want spring layers and rain protection.
Is the sea warm enough to swim in April?
The sea is cold, averaging 10.2°C, with a year-to-year range of 9°C to 11°C. That is well below the 22°C benchmark for swimming, so April does not suit a trip built around comfortable sea swims.
Would another month be better for a warmer trip?
If warmth matters more than mild walking weather, June, July and August are better choices overall. April suits travellers happy to wear layers and work around rain; it is not the month to choose for dependable heat.
About these averages
ERA5-Land climate reanalysis via Open-Meteo (11 km grid) and NOAA Coral Reef Watch 5 km sea temperatures, 1991-2020
Averages computed from daily values at Istanbul. Sea temperature from the nearest 5 km sea cell, 2.5 km from that point. Sunshine hours are estimated from average cloud cover.Records are the highest and lowest daily values in that 30-year period, not all-time records. These are climate averages, not a forecast for your trip. How we measure holiday weather
- Hot · 25°C+
- Warm · 20°C to below 25°C
- Mild · 15°C to below 20°C
- Cool · below 15°C