None of the data on the map is 'real time'.
Note: This is not a typical map legend that is a single graphic image that has a list of all the symbology you see on the map. Instead, this legend is text combined with links to legend graphics that are hosted on various GIS servers.
The fire maps I produce can display three kinds of information.
1. MODIS/VIIRS satellite heat detection
Triangle = MODIS (less accurate)
Square = VIIRS (more accurate)
The colors show when heat was detected.
Dark red: Less than 6 hours ago
Red: From 6 to 12 hours ago
Orange: From 12 to 24 hours ago
Yellow: From 24 hours ago to 7 days
July 12, 2022 update
Due to technology improvements at NASA the MODIS/VIIRS data can appear on the map within 20 minutes of when the satellite detects a heat source. This is a huge improvement since previously there was a 3-4 hour delay before that data could appear on the map. Also this data is now colored-coded to show its age. The darker data is a more recent heat detection. The map also now shows 7 days of MODIS/VIIRS data instead of about 30 hours.
Satellite hotspot locations are approximate. A MODIS hotspot represents a box 1,000 meters (~0.62 miles) by 1,000 meters. The actual detection could be anywhere inside that box. A VIIRS hotspot represents a box 375 meters (~0.23 miles) by 375 meters.
A satellite hotspot can be a 'false positive' when (1) the fire is near the edge of the 'strip' of land that the satellite sees and (2) there is heavy smoke with hot embers. High wind can also be a factor in 'false positive' hotspots being detected. Likewise, an area can burn and never show up on the map as a hotspot. This can happen when a grassy area burns just after a satellite pass and then cools before the next satellite pass.
2. Fire perimeter and related data
If the map shows a red/black fire perimeter, then here is the legend for that data. Currently you cannot turn this data off. That feature will be added in the future.
Red and black line = Fire perimeter
White line = Estimated perimeter
Red shaded = Intense fire
Yellow shaded = Scattered fire
Red dot = Isolated fire
Blue box = No infrared data
Grayed out areas = Heavy clouds affected infrared data
Fire perimeters are typically produced at night by fire staff who analyze infrared data from a nighttime overflight. The perimeter data is then used on a wide variety of maps for the coming day. The infrared analyst also identifies areas of intense, scattered and isolated heat.
If you turn on the overlay layer "Fire perimeter NIFC" then the pink area shows what has burned.
Updated fire perimeter data might be publically available only once every 24 hours. Also it is always possible that not everything inside the perimeter burned.
2. Date layers hosted on GIS servers
Most GIS overlay layers that this map can display only have a single type of symbol. To see what symbol is used for a layer you can turn the layer on/off a couple of times. The symbol used for that layer should be obvious. Note that some overlay layers might be defined on the GIS server so that they only display at certain zoom levels. You might need to zoom in or out for the data to display. And if the GIS server hosting the data is busy it might take more than a few seconds for the data to appear on the map.
A few GIS overlay layers have multiple symbols or colored areas that mean different things. Those layers are listed below along with a link to the legend graphic which is hosted on the GIS server. Look at the layer number in the list below and then find that same layer number in the legend graphic.
Use your 'back' button after visiting any of these links.
CLICK HERE to see the legend for: