Best Time to Fly to Avoid Turbulence, by Month and Hour

month by month

The bumpiest and calmest months, region by region

How often the air at cruise height over each region is bumpy, in each month. Read along a row to find the calm season where you are flying.

Share of the time the air at cruise height is bumpy, by month
	J	F	M	A	M	J	J	A	S	O	N	D
North America	29	28	26	25	24	21	18	19	21	24	27	29
South America	9	9	8	10	14	15	15	16	14	13	12	12
Europe	16	15	16	19	21	21	23	21	20	18	19	16
Asia	29	31	32	29	25	19	16	14	15	16	20	26
Africa	18	16	16	13	10	6	6	7	5	6	10	14
Australia and Oceania	13	12	14	20	28	33	28	25	24	23	26	17

Each number is the % of the time the air at cruise height (about 30,000–34,000 ft) is light-or-worse bumpy in that month, averaged over every year in the report.

why the seasons differ

Winter is the jet stream. Summer is storms.

The jet stream is driven by the temperature difference between the poles and the tropics, and that difference is largest in winter. So in each hemisphere's winter the jet is fastest, and the wind shear around it, the main source of turbulence at cruise height, is strongest. In the north that is December to March; in the south, June to September.

Summer swaps that for heat. Sun-warmed ground drives rising air, and where there is moisture it builds into thunderstorms. Crews fly around storms, but the air around them is bumpy too. In the tropics the storm season is the wet season, and it moves with the monsoon.

So the calmest time to fly is usually spring or autumn, between the two: the jet has weakened and the storms have not started, or have stopped.

the hotspots

Month by month over the places pilots talk about

Share of the time the air at cruise height is bumpy, by month
	J	F	M	A	M	J	J	A	S	O	N	D
North Atlantic	41	40	37	33	28	28	26	29	33	36	41	38
Rocky Mountains	38	43	37	31	29	27	15	17	22	27	36	40
Andes	16	17	18	28	35	42	41	44	40	35	31	26
Himalayas and Tibet	53	54	50	44	37	24	11	8	14	26	34	48
Bay of Bengal	7	9	8	4	5	10	14	11	7	2	2	7
Alps	35	31	30	25	20	21	23	20	28	28	36	32
Japan	52	55	52	55	52	46	25	22	33	41	50	56
Tasman Sea and New Zealand	26	27	28	26	27	30	30	27	27	29	28	33

Each number is the % of the time the air at cruise height (about 30,000–34,000 ft) is light-or-worse bumpy in that month, averaged over every year in the report.

time of day

The smoothest time of day to fly

By local departure time, averaged over every ranked route in each region. Mornings are usually calmest over land, before the ground heats up; over the sea, storms peak at night instead.

All routesMorning17%Afternoon19%Evening18%Night17%

United StatesMorning22%Afternoon25%Evening24%Night23%

EuropeMorning19%Afternoon19%Evening19%Night19%

AsiaMorning19%Afternoon21%Evening19%Night19%

Australia and NZMorning13%Afternoon15%Evening14%Night14%

South AmericaMorning10%Afternoon15%Evening11%Night11%

Share of flight time in bumpy air by local departure time, averaged over every ranked route. The smoothest time of day is in green.

in short

How to pick a smoother flight

✓Fly early in the day in summer and in the tropics, before the ground heats up and storms build.
✓Avoid the local winter on jet-stream routes: Japan, Korea, the North Atlantic and the southern Andes are calmest from late spring to early autumn.
✓Over mountains, watch the wind, not the calendar. A calm day over the Rockies or the Alps can be glassy in any month.
✓Check the forecast for your actual flight. The season tells you the odds; the forecast tells you the day.

Forecast your flight

Questions about the best time to fly

What is the best month to fly to avoid turbulence?

Worldwide, September. For a specific region, read along its row in the month-by-month table above: in the northern hemisphere the calm season is late spring to early autumn, in the south it is the southern summer.

What time of day is best to fly to avoid turbulence?

Over land, the morning. The ground has not heated up, so there are no thermals near the airport and the afternoon storms have not built. Over warm seas, storms peak at night instead, so the advantage is smaller there.

Is turbulence worse in winter or summer?

At cruise height, winter, because the jet stream is strongest. Near the ground and in the tropics, summer, because of heat and storms. Which one you notice depends on the route.

Is it smoother to fly at night?

Over land, often: no thermals, and most inland storms collapse after sunset. But the jet stream does not care what time it is, so a winter night flight under it is no smoother than a day one.

More from the Turbulence Report

Turbulence Report The world's most turbulent routes, airports and countries, ranked from 6,988 global weather snapshots since 2022. With the method and the data. Most turbulent routes The 25 most turbulent flight routes in the world, ranked by the share of the flight in bumpy air, with the cause and worst month of each. Is turbulence dangerous? A straight answer: turbulence is uncomfortable, not structurally dangerous, and the real risk is being unbelted. What causes it, and why it feels worse than it is. Turbulence forecast Check the turbulence forecast for any route, free. Enter two airports and see where the air gets bumpy, how long it lasts and why.

The best time to fly to avoid turbulence