Where would today's winds carry fallout near Los Angeles, California?
The map below estimates where today's forecast upper-air winds would carry fallout from each potential target near Los Angeles, and whether any of it could reach the city.
Los Angeles is itself on this site's list of potential targets. Close to an explosion, blast and heat are the main dangers, and fallout would begin within minutes whatever the wind.
There are 4 other listed targets in range of Los Angeles. The nearest is San Diego, about 111 miles to the southeast.
Winds high above the continental United States blow from the west more often than not, so targets to the west of Los Angeles are upwind most often: Vandenberg SFB. On any given day the pattern can be quite different, which is what the map below shows.
Listed targets in range of Los Angeles (illustrative, not a prediction)
| Potential target | Type | From Los Angeles |
|---|---|---|
| Los Angeles, CA | Metro area | Here |
| San Diego, CA | Metro area | 111 mi southeast |
| Vandenberg SFB, CA | Military site | 141 mi west-northwest |
| Nellis AFB / Las Vegas, NV | Military site | 236 mi northeast |
| San Francisco, CA | Metro area | 347 mi northwest |
Many factors affect where fallout travels and how dangerous it is. This educational tool takes only three into account: the forecast winds from the ground up to the top of the mushroom cloud, an assumed weapon size, and an assumed burst type (on the ground or in the air). The target list is illustrative, not a prediction. How to read the map.
Estimated fallout paths from potential targets
- Estimated path that could reach you
- Estimated path that misses you
- You
What this map takes into account. Many factors affect where fallout travels and how dangerous it is. This educational tool takes only three into account: the forecast winds from the ground up to the top of the mushroom cloud, an assumed weapon size, and an assumed burst type (on the ground or in the air).
It takes into account:
- Forecast winds at every altitude: speed and direction from the ground to the top of the mushroom cloud, at each target and at points around you, hour by hour for up to 12 hours of travel.
- Assumed weapon size: the size you select, which sets how high the cloud rises and how far this model draws the path.
- Assumed burst type: ground bursts for military sites, and your choice of ground or air for cities. A ground burst produces heavy local fallout; an air burst produces little.
It does not take into account:
- The weapons actually used: their real size, design, number and height of burst, none of which can be known in advance.
- Radiation dose: how strong the radiation would be at any place or time.
- Rain and snow: precipitation is flagged, but the hotspots it creates are not mapped.
- Terrain and local weather: hills, valleys, storms and small-scale winds between forecast points.
- Particle sizes: heavier particles fall sooner and nearer than light ones, which makes real patterns uneven.
- Forecast error: the result is only as good as the weather forecast behind it.
- What would actually be targeted: the target list is illustrative, not a prediction.
Treat the paths as a rough guide to what is likely, not a prediction. How it works.
Next 48 hours
How many of these targets would send fallout to you as the weather changes. Select a time to see it on the map.
Winds above you
Official preparedness guidance
This is a summary of public guidance from Ready.gov and the CDC. It does not come from this map, and the map should not be used to make emergency decisions.
- Get inside. Official guidance is to get into the nearest solid building, as deep and central as possible: a basement, or the middle of a large building.
- Stay inside. Official guidance is to stay sheltered for at least 24 hours unless authorities say otherwise, because fallout radiation is strongest in the first hours and decays quickly.
- Stay tuned. Follow official instructions, for example by battery-powered or hand-crank radio.
Read the sources: Ready.gov: Radiation Emergencies and CDC: Radiation Emergencies. Our fuller summary lists each source.