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Nerd mode: every forecast, readouts, filters and range & bearing for weather enthusiasts

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Nerd mode: every forecast, readouts, filters and range & bearing for weather enthusiasts

This week’s weatherIstanbul, Turkey

Rain is likely in Istanbul on Tuesday

Nearly all of NOAA’s 31 GEFS forecasts bring measurable rain to Istanbul Tue 3–9 a.m. GMT+3; 8 in 10 bring 2.5 mm or more.

NOAA GEFS, 31 forecasts · Mon 28 Sep 18Z run · updated Tues., Sept. 29, 2:03 a.m. GMT+3 · times are Istanbul’s (GMT+3)

See it on the globe For warnings, follow your national weather service.

Quick answers

Will it rain in Istanbul this week?
The best chances of measurable rain: Tuesday (nearly all forecasts, 3–9 a.m.); Wednesday (9 in 10 forecasts, 9 p.m.–3 a.m.); Thursday (7 in 10 forecasts, 9 a.m.–3 p.m.); Friday (9 in 10 forecasts, 9 p.m.–3 a.m.). Times are GMT+3.
How much rain will Istanbul get this week?
By Mon., Oct. 5, 9 p.m. GMT+3 (the end of the forecast), the middle forecast has 35 mm of rain and melted snow, counting from Tue 3 a.m. 8 in 10 forecasts bring 25 mm or more in total; 2 in 10 forecasts bring 51 mm or more.
How windy will it get in Istanbul?
Gusts over 48 km/h: 2 in 10 forecasts at Sat 3 p.m. GMT+3. The middle forecast’s strongest gust is 44 km/h, Wed 3 p.m. Checked every six hours, so a brief peak can fall between.
How warm or cold will it be in Istanbul?
At the six-hourly times, the middle forecast runs from 15°C (Mon., Oct. 5, 3 a.m.) to 20°C (Wed 3 p.m.) GMT+3. The day’s real high and low can fall between those times.
Are any storms heading for Istanbul?
No storm Stormlines tracks has 1 in 10 forecasts passing its centre within 160 kilometres of Istanbul this week.

Chance of rain, six hours at a time

Tue 3–9 a.m.: nearly all forecasts with measurable rain; middle forecast 4.1 mmTue 9 a.m.–3 p.m.: nearly all forecasts with measurable rain; middle forecast 4.7 mmTue 3–9 p.m.: 9 in 10 forecasts with measurable rain; middle forecast 3.1 mmTue 9 p.m.–3 a.m.: 9 in 10 forecasts with measurable rain; middle forecast 1.7 mmWed 3–9 a.m.: 7 in 10 forecasts with measurable rain; middle forecast 1.0 mmWed 9 a.m.–3 p.m.: 7 in 10 forecasts with measurable rain; middle forecast 0.7 mmWed 3–9 p.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneWed 9 p.m.–3 a.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneThu 3–9 a.m.: 5 in 10 forecasts with measurable rain; middle forecast almost noneThu 9 a.m.–3 p.m.: 7 in 10 forecasts with measurable rain; middle forecast 0.6 mmThu 3–9 p.m.: 7 in 10 forecasts with measurable rain; middle forecast 0.5 mmThu 9 p.m.–3 a.m.: 9 in 10 forecasts with measurable rain; middle forecast 1.5 mmFri 3–9 a.m.: 8 in 10 forecasts with measurable rain; middle forecast 1.7 mmFri 9 a.m.–3 p.m.: 8 in 10 forecasts with measurable rain; middle forecast 0.7 mmFri 3–9 p.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmFri 9 p.m.–3 a.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmSat 3–9 a.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.4 mmSat 9 a.m.–3 p.m.: 6 in 10 forecasts with measurable rain; middle forecast 0.5 mmSat 3–9 p.m.: 4 in 10 forecasts with measurable rain; middle forecast almost noneSat 9 p.m.–3 a.m.: 3 in 10 forecasts with measurable rain; middle forecast almost noneSun 3–9 a.m.: 3 in 10 forecasts with measurable rain; middle forecast almost noneSun 9 a.m.–3 p.m.: 4 in 10 forecasts with measurable rain; middle forecast almost noneSun 3–9 p.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneSun 9 p.m.–3 a.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneMon 3–9 a.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneMon 9 a.m.–3 p.m.: 3 in 10 forecasts with measurable rain; middle forecast almost noneMon 3–9 p.m.: 2 in 10 forecasts with measurable rain; middle forecast almost none

Each bar is the share of the 31 forecasts with measurable rain or melted snow in that six hours; the darker the bar, the more forecasts agree. Local days, GMT+3.

The week, day by day

DayChance of rain2.5 mm or moreTotal by day’s endStrongest gustTemperature
Tue 29 (rest of day)nearly all8 in 1014 mm · 5 in 1041 km/h18°C–18°C
Wed 309 in 103 in 1018 mm · 7 in 1044 km/h18°C–20°C
Thu 17 in 101 in 1023 mm · 8 in 1038 km/h17°C–19°C
Fri 29 in 103 in 1029 mm · 9 in 1036 km/h17°C–19°C
Sat 36 in 103 in 1033 mm · nearly all40 km/h16°C–18°C
Sun 44 in 101 in 1033 mm · nearly all35 km/h15°C–18°C
Mon 53 in 10<1 in 1035 mm · nearly all29 km/h15°C–18°C

Chances are the highest in any six hours of the day. “Total by day’s end” is the middle forecast’s running total since Tue 3 a.m., and the share of forecasts with 13 mm or more by then; totals aren’t added up day by day, because the middle forecast of each day isn’t the same forecast. Gusts and temperatures are read every six hours.

Storms near Istanbul

No storm Stormlines tracks has 1 in 10 forecasts passing its centre near Istanbul this week. Every storm we’re tracking →

About these numbers

They come from one source, NOAA’s Global Ensemble Forecast System (GEFS): 31 runs of the same model, each started slightly differently, read at Istanbul’s coordinates on a grid about 55 km (35 miles) apart. “8 in 10 forecasts” means 8 in 10 of those runs. Nothing is adjusted for local effects such as coasts, lakes, hills or city heat, so the numbers can differ from your local official forecast, especially for snow and showers.

“Measurable rain” counts rain or melted snow in a six-hour period. Not an official forecast: follow your national weather service for warnings and decisions. How the forecasts are read: how to read the maps and the glossary.

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