Bay water is not the coastal ocean
The National Weather Service’s Miami marine directory identifies Biscayne Bay as AMZ630. AMZ651 covers coastal waters from Deerfield Beach to Ocean Reef out to 20 nautical miles. Those names matter: a forecast for one area should not be silently used for another. Choose the part of this page that matches the water you intend to visit, and open NOAA’s map if you are unsure about the boundary.
NOAA sometimes issues one bulletin for multiple zones. When the coastal feed includes an additional zone, we retain its code above the forecast. For example, AMZ671 is the separate offshore zone from 20 to 60 nautical miles. A combined bulletin is not a more precise forecast for a beach, channel or marina. We do not turn it into one by placing “Key Biscayne” in the heading.
Three times worth checking
“Issued” is when NOAA prepared the forecast. “Product expires” is the expiry carried by the source. “Retrieved” is when this guide obtained it. A recent retrieval cannot make yesterday’s bulletin new. Our reader checks those clocks and the zone before displaying the forecast, and removes data that expires while the page remains open.
The page checks again every 15 minutes while open and when you return to the tab. It can still be unavailable if NOAA cannot be reached or its format changes. In that case, use the direct source link and check its timestamp yourself. NOAA’s marine directory warns that timely internet delivery is not guaranteed. This page should not be your only source of urgent information.
Keep the forecast wording intact
The periods above retain NOAA’s wording rather than reducing a whole day to a green or red badge. Read the full period, including thunderstorm mentions and changes later in the day. The source may use abbreviations such as “kt” for knots, “NM” for nautical miles and “tstms” for thunderstorms. The official NWS glossary is available for unfamiliar terms.
A forecast is not a report from your boat or the shoreline. The Virginia Key NDBC station supplies local observations used elsewhere in this guide. Its measurements and their observation times belong to a different evidence layer. Neither a single sensor nor a regional forecast guarantees the conditions at a particular launch.
Tides, warnings and the rest of the trip
For local tide information, the NOAA Virginia Key station is the reference used by this site. A tide prediction is not a current-depth measurement or a clearance calculation for your vessel. This page deliberately avoids route instructions and automatic “safe to go” recommendations.
Use the official warning links above even when a forecast card loads successfully. We preserve any warning headline contained in the forecast, but do not aggregate every Special Marine Warning or Marine Weather Statement here. An absent headline is not an all-clear signal. Check the source that applies to your location and time.
Check access separately
If your trip starts at Crandon, the marina guide separates published launch fees and office hours from live space availability. The causeway page covers reported road incidents. Keep those checks separate from weather: an open route to the island does not reserve a ramp space, and a marina’s published hours say nothing about wind or waves.