A tropical wave that moved off Africa on 8 July crossed Central America and organized over the eastern North Pacific into a tropical depression at 0600 UTC 22 July 2017 about 550 nautical miles south of the southern tip of the Baja California Peninsula. The system became Tropical Storm Irwin by 0600 UTC 23 July and moved generally west to west‑northwest over open ocean. Irwin persisted for about 10 days, executing a small loop late on 27–29 July while interacting with nearby Hurricane Hilary, and weakened to a remnant low by 1800 UTC 1 August before dissipating over the central North Pacific on 3 August.
Irwin remained well offshore for its entire life; there were no coastal watches or warnings and the storm made no landfalls.
The storm reached its maximum intensity near 1800 UTC 25 July with maximum sustained winds of 80 kt (about 92 mph) and a minimum central pressure of 979 mb, corresponding to a Category 1 hurricane on the Saffir‑Simpson scale. Irwin maintained hurricane strength only briefly (around 25–26 July) before stronger wind shear from Hurricane Hilary caused rapid weakening back to tropical‑storm strength.
Because Irwin stayed over open water, there were no reports of storm surge impacts or rainfall totals at land sites in the NHC report. No ship reports of tropical‑storm‑force winds were received, and no specific storm‑surge heights or rainfall accumulations for populated locations were documented.
There were no reports of damage or casualties associated with Irwin. The primary impacts were confined to the ocean; no deaths (direct or indirect) or property losses were reported.
Noteworthy aspects include the favorable forecasting of Irwin’s formation (NHC increased genesis probabilities well in advance) and generally good official track and intensity forecasts for this storm. Forecast models struggled to capture the interaction between Irwin and Hurricane Hilary, with many models incorrectly predicting a merger, but the official forecasts performed near or better than recent averages.
Paid members can generate summaries tailored to the counties of their choice. The Irwin TCR covers impacts across many counties and states — a Pinellas County resident doesn't need the Asheville detail, and a Buncombe County resident doesn't need the Tampa surge data.
Upgrade for county-specific summariesSummary above produced from the National Hurricane Center's official post-storm Tropical Cyclone Report. Read the full report for casualty lists, damage estimates by area, forecast critique, and detailed meteorological discussion:
📄 Read NHC's full report on Irwin → (opens at nhc.noaa.gov)| Time (UTC) | Status | Lat | Lon | Winds (kt) | Pressure (mb) | Record |
|---|---|---|---|---|---|---|
| 2017-07-22 06:00 | TD | 14.10 | -111.70 | 30 | 1006 | |
| 2017-07-22 12:00 | TD | 14.30 | -112.40 | 30 | 1006 | |
| 2017-07-22 18:00 | TD | 14.50 | -113.20 | 30 | 1006 | |
| 2017-07-23 00:00 | TD | 14.60 | -114.00 | 30 | 1006 | |
| 2017-07-23 06:00 | TS | 14.70 | -114.80 | 35 | 1005 | |
| 2017-07-23 12:00 | TS | 14.80 | -115.50 | 35 | 1004 | |
| 2017-07-23 18:00 | TS | 14.80 | -116.20 | 40 | 1003 | |
| 2017-07-24 00:00 | TS | 14.80 | -116.70 | 45 | 1001 | |
| 2017-07-24 06:00 | TS | 14.80 | -117.00 | 50 | 999 | |
| 2017-07-24 12:00 | TS | 14.90 | -117.30 | 55 | 996 | |
| 2017-07-24 18:00 | TS | 15.00 | -117.60 | 60 | 993 | |
| 2017-07-25 00:00 | HU | 15.20 | -118.10 | 65 | 990 | |
| 2017-07-25 06:00 | HU | 15.40 | -118.60 | 70 | 986 | |
| 2017-07-25 12:00 | HU | 15.60 | -119.20 | 75 | 983 | |
| 2017-07-25 18:00 | HU | 15.80 | -119.80 | 80 | 979 | |
| 2017-07-26 00:00 | HU | 15.90 | -120.50 | 80 | 979 | |
| 2017-07-26 06:00 | HU | 15.80 | -121.20 | 70 | 987 | |
| 2017-07-26 12:00 | TS | 15.60 | -121.80 | 55 | 994 | |
| 2017-07-26 18:00 | TS | 15.30 | -122.50 | 50 | 999 | |
| 2017-07-27 00:00 | TS | 15.00 | -123.00 | 50 | 999 | |
| 2017-07-27 06:00 | TS | 14.90 | -123.50 | 50 | 999 | |
| 2017-07-27 12:00 | TS | 14.90 | -123.90 | 50 | 999 | |
| 2017-07-27 18:00 | TS | 14.90 | -124.20 | 50 | 999 | |
| 2017-07-28 00:00 | TS | 14.90 | -124.40 | 50 | 999 | |
| 2017-07-28 06:00 | TS | 14.90 | -124.60 | 50 | 998 | |
| 2017-07-28 12:00 | TS | 14.80 | -124.70 | 50 | 998 | |
| 2017-07-28 18:00 | TS | 14.70 | -124.70 | 50 | 998 | |
| 2017-07-29 00:00 | TS | 14.70 | -124.60 | 50 | 998 | |
| 2017-07-29 06:00 | TS | 14.80 | -124.50 | 50 | 998 | |
| 2017-07-29 12:00 | TS | 15.00 | -124.40 | 50 | 998 | |
| 2017-07-29 18:00 | TS | 15.40 | -124.40 | 50 | 998 | |
| 2017-07-30 00:00 | TS | 16.00 | -124.50 | 55 | 997 | |
| 2017-07-30 06:00 | TS | 16.70 | -124.70 | 55 | 997 | |
| 2017-07-30 12:00 | TS | 17.40 | -124.90 | 55 | 997 | |
| 2017-07-30 18:00 | TS | 18.30 | -125.40 | 55 | 998 | |
| 2017-07-31 00:00 | TS | 19.20 | -126.00 | 55 | 999 | |
| 2017-07-31 06:00 | TS | 20.20 | -126.50 | 50 | 1000 | |
| 2017-07-31 12:00 | TS | 21.20 | -127.00 | 50 | 1001 | |
| 2017-07-31 18:00 | TS | 22.20 | -127.50 | 50 | 1002 | |
| 2017-08-01 00:00 | TS | 23.30 | -128.00 | 45 | 1004 | |
| 2017-08-01 06:00 | TS | 24.40 | -128.50 | 45 | 1006 | |
| 2017-08-01 12:00 | TS | 25.50 | -129.00 | 35 | 1008 | |
| 2017-08-01 18:00 | LO | 26.40 | -129.50 | 30 | 1008 | |
| 2017-08-02 00:00 | LO | 27.30 | -130.10 | 30 | 1009 | |
| 2017-08-02 06:00 | LO | 27.90 | -130.80 | 30 | 1009 | |
| 2017-08-02 12:00 | LO | 28.30 | -131.40 | 25 | 1010 | |
| 2017-08-02 18:00 | LO | 28.40 | -131.60 | 20 | 1011 | |
| 2017-08-03 00:00 | LO | 28.40 | -131.60 | 20 | 1012 | |
| 2017-08-03 06:00 | LO | 28.40 | -131.60 | 15 | 1013 | |
| 2017-08-03 12:00 | LO | 28.40 | -131.30 | 15 | 1013 |
Source: NOAA National Hurricane Center HURDAT2 best-track database (nhc.noaa.gov/data). Data is in the public domain. Best-track positions and intensities are post-storm reanalysis estimates and may differ from real-time advisories.