How ChartTheWind works

Reading a report

What the charts and tables are showing.

The pictures below come from a sample report for Hurricane Ian at one Fort Myers, FL address, September 27–28, 2022. They show how the wind’s direction and strength changed through the event, in plain terms.

The at-a-glance numbers and the direction timeline

Sample report: Hurricane Ian, Fort Myers, FL, 2022-09-27 to 2022-09-28

The row of tiles at the top is a quick summary of how the wind’s direction behaved:

• Total direction change and major transitions: how far the wind direction turned in total, and how many times it settled into a new general direction.
• Longest quadrant duration: the longest uninterrupted stretch from one general direction, here 8.0 hours of easterly wind.
• Direction variability and fluctuation: how jumpy the direction was. Steady wind holds its direction; turbulent, gusty wind wobbles back and forth. “Fluctuation events” counts the times the direction was noticeably unsteady.
• Wind shifts (NWS): a sharp turn of 45° or more in under 15 minutes while the wind was steady at 10 knots or more. This sample had none.

The direction timeline breaks the event into “regimes”: periods of at least an hour when the wind came mostly from one general direction, such as easterly or northeasterly. Each colored block is one regime and shows how long it lasted, and the red line underneath is the wind speed. A new direction only counts once it has held, so brief wobbles don’t get mistaken for a real change.

The direction chronology below it is the same event reading by reading. Each arrow shows which way the wind was blowing at that moment, the blue line is sustained wind, the red line is gusts, and shaded areas mark stretches where the direction was jumpy.

How long the wind came from each direction

Sample report: Hurricane Ian, Fort Myers, FL, 2022-09-27 to 2022-09-28

The occupancy table answers “which direction did the wind come from, and for how long?” For each direction it lists the total hours, the longest single stretch, how many separate times the wind returned to that direction, and the strongest gust from it. In this sample the wind was from the east for 21.3 hours in total, in blocks of up to 8.0 hours, returning five times, with a peak gust of 57.9 mph.

The persistence table on the right describes how steady or changeable the event was overall: how long a typical pattern lasted, how often the direction changed per hour, and how much the direction fluctuated within 1-hour, 2-hour and longer windows. A long stretch from one direction means the same side of a building faced the wind for a long time; repeated shorter returns mean it was hit again and again.

How the wind moved from one direction to the next

Sample report: Hurricane Ian, Fort Myers, FL, 2022-09-27 to 2022-09-28

The transition map is a compass with numbered dots. The dots follow the order of the direction patterns during the event, placed where each one sat on the compass, and the lines join them in sequence. In this sample they stay clustered between northeast and southeast, which shows the wind swinging within that range instead of sweeping around the whole compass.

The transition summary cards put the same story into words: each one says what the wind changed from and to, and when the change began (in UTC time).

The wind event summary compares the estimated winds at the property with National Weather Service wind advisory criteria. For each category it shows how many readings reached it, when it first and last occurred, and the peak value and time. In this sample, gusts reached the advisory range of 46–57 mph in 14 readings, with a peak of 57.9 mph. Wind of 25 mph or more held for 132 minutes in a row, peaking at 36.3 mph. These categories are modelled on NWS criteria; they are not official warnings issued for the property.