CME arrival verification
NASA issues a forecast of when each Earth-directed coronal mass ejection (CME) should arrive. NASA also records when the resulting interplanetary shock actually reached Earth. This page sets the two side by side, one row per forecast, and keeps every row, including forecasts that arrived earlier or later than the window. SolarStormAlert does not issue these forecasts; it relays NASA's and compares them with NASA's own records. Limits of the comparison ↓
Source: NASA DONKI (CME analyses and IPS) via CCMC · our L1 log: SolarStormAlert shock log from NOAA SWPC solar wind data · compiled UTC · refreshed within 10 min
Summary
Of 43 NASA forecasts with a stated arrival window and a recorded outcome, issued 2026-06-02 to 2026-10-12: 10 arrived inside the window, 11 arrived earlier, 8 arrived later, and 14 have no arrival recorded.
- Arrived inside the window 10
- Arrived earlier than the window 11
- Arrived later than the window 8
- No arrival recorded 14
For the 19 forecasts that arrived earlier or later, the median distance outside the window was 9.1 h (n = 19).
These are counts of NASA forecasts against NASA's own records. They do not rate NASA or SolarStormAlert.
Limits of the comparison
- Matching uses NASA's own links. A forecast is paired with an arrival only when NASA's interplanetary-shock record (IPS) names the same CME activity ID as the forecast. We never pair events because they are close in time.
- Several CMEs can share one arrival. When NASA links more than one CME to a single recorded arrival, each forecast is compared with that arrival on its own, so the same arrival can appear in more than one row.
- Combined forecasts cover several CMEs. When one NASA forecast models several CMEs together, its row is compared with the first arrival NASA links to any of those CMEs, which can be a companion CME's arrival rather than the one the forecast mainly describes. Such rows are labelled as covering several CMEs.
- Each row uses one forecast. The forecast of record is the latest NASA notification with a stated arrival window that was issued before NASA's recorded arrival, so later notifications never change the comparison. NASA often updates a forecast; each row shows how many notifications NASA issued.
- "No arrival recorded" is about NASA's catalogue. It means NASA's IPS record holds no shock linked to that CME more than 72 hours after the forecast window closed. NASA's records can lag, and a CME can pass Earth without a measurable shock. A row can change if NASA adds a record later.
- "Pending" means the comparison is not finished. NASA has not recorded an arrival yet, and either the window has not closed or the 72-hour period after it has not ended. Forecasts where NASA gave no arrival window are listed as "No arrival window stated" and are not counted.
- Our own L1 detection is a second observation. Our detector reads NOAA SWPC's real-time solar wind feed from spacecraft at the L1 point. Its log begins 2026-08-01 UTC, so earlier rows carry no detection information; the earliest entries were taken from our alert records. A detection is shown when it falls within 3 hours of NASA's recorded arrival. It only flags strong shocks (a solar-wind speed jump of at least 100 km/s), so weaker arrivals that NASA records often show no detection here. It never changes a row's outcome. Our L1 log appears only next to a NASA forecast, so a shock we logged at an arrival with no Earth-directed forecast of its own is not listed here.
- This page compares records. SolarStormAlert does not issue these forecasts. The page sets NASA's forecasts beside NASA's records and does not rate any forecaster.
The record
In each row's shape, the outlined bar is NASA's forecast window and the dot is when NASA recorded the arrival.
October 2026
Arrived later than the forecast window
9.1 h after the window closed
CME 2026-10-11T23:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 14.4 h after
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
22.6 h before the window opened
CMEs 2026-10-08T16:53:00-CME-001, 2026-10-08T16:24:00-CME-001 (combined forecast covering several CMEs)
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 28.5 h before
- Our L1 detection
- UTC · our L1 log
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
24.5 h before the window opened
CME 2026-10-08T16:24:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 31.5 h before
- Our L1 detection
- UTC · our L1 log
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived later than the forecast window
14.3 h after the window closed
CME 2026-10-06T06:23:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 19.9 h after
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
September 2026
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-09-28T14:36:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
1.1 h before the window opened
CME 2026-09-14T11:08:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 8.1 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived earlier than the forecast window
3.6 h before the window opened
CME 2026-09-13T21:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 10.6 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived earlier than the forecast window
17.5 h before the window opened
CME 2026-09-13T19:48:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 24.5 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 3 (first UTC)
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-09-06T10:53:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
7.5 h before the window opened
CMEs 2026-09-05T11:09:00-CME-001, 2026-09-05T18:09:00-CME-001 (combined forecast covering several CMEs)
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 14.5 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 3 (first UTC)
Arrived earlier than the forecast window
10.9 h before the window opened
CME 2026-09-05T18:09:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 18.0 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
August 2026
Arrived inside the forecast window
1.2 h before the window centre
CME 2026-08-25T10:38:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 1.2 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 3 (first UTC)
Arrived inside the forecast window
0.9 h before the window centre
CMEs 2026-08-25T12:53:00-CME-001, 2026-08-25T10:38:00-CME-001 (combined forecast covering several CMEs)
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 0.9 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived later than the forecast window
4.1 h after the window closed
CME 2026-08-14T05:09:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 11.1 h after
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived inside the forecast window
1.3 h before the window centre
CME 2026-08-08T03:23:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 1.3 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-08-08T08:15:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived inside the forecast window
4.1 h before the window centre
CME 2026-08-04T13:23:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 4.1 h before
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-08-04T11:23:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
July 2026
Arrived later than the forecast window
0.4 h after the window closed
CME 2026-07-30T16:53:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 11.0 h after
- Our L1 detection
- No strong shock detected within 3 h of NASA's recorded arrival
- Forecast of record
- UTC
- Notifications issued
- 3 (first UTC)
Arrived later than the forecast window
8.2 h after the window closed
CME 2026-07-24T04:38:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 15.0 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-07-21T15:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-07-20T19:53:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-07-12T01:14:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived inside the forecast window
3.6 h after the window centre
CMEs 2026-07-11T01:23:00-CME-001, 2026-07-11T04:38:00-CME-001 (combined forecast covering several CMEs)
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 3.6 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived later than the forecast window
0.5 h after the window closed
CME 2026-07-10T15:53:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 9.4 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived later than the forecast window
0.8 h after the window closed
CME 2026-07-09T07:53:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 4.7 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
3.0 h before the window opened
CME 2026-07-07T22:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 10.0 h before
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-07-05T17:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-07-03T18:36:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived earlier than the forecast window
19.2 h before the window opened
CMEs 2026-07-01T12:12:00-CME-001, 2026-07-01T21:12:00-CME-001, 2026-07-02T02:36:00-CME-001 (combined forecast covering several CMEs)
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 26.2 h before
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
9.1 h before the window opened
CME 2026-07-02T02:36:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 15.1 h before
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived earlier than the forecast window
15.0 h before the window opened
CME 2026-07-01T21:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 22.0 h before
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived inside the forecast window
3.4 h after the window centre
CME 2026-06-30T21:45:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 3.4 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 3 (first UTC)
June 2026
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-06-29T22:24:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived inside the forecast window
at the window centre
CME 2026-06-26T21:12:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- at the window centre
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-06-12T16:36:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 2 (first UTC)
Arrived inside the forecast window
6.8 h after the window centre
CME 2026-06-11T00:36:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 6.8 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived later than the forecast window
19.9 h after the window closed
CME 2026-06-06T14:11:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 26.4 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 3 (first UTC)
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-06-04T23:00:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
Arrived inside the forecast window
2.9 h after the window centre
CMEs 2026-06-03T01:53:00-CME-001, 2026-06-03T11:48:00-CME-001 (combined forecast covering several CMEs)
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 2.9 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 5 (first UTC)
Arrived inside the forecast window
4.4 h after the window centre
CME 2026-06-03T11:48:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- UTC
- From window centre
- 4.4 h after
- Our L1 detection
- Not available: our log begins UTC
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-06-03T07:23:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1
No arrival recorded
NASA's IPS record holds no shock linked to this CME, more than 72 h after the window closed.
CME 2026-06-02T17:23:00-CME-001
- Forecast window
- to UTC
- NASA recorded arrival
- None recorded
- Forecast of record
- UTC
- Notifications issued
- 1