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UV Index Scale
The UV Index scale conforms with international guidelines for UVI reporting established by the World Health Organization. What follows is a description of each UV Index level and tips to help you avoid harmful exposure to UV radiation.
2 or less: Low
A UV Index reading of 2 or less means low danger from the sun's UV rays for the average person.
- Wear sunglasses on bright days. In winter, reflection off snow can nearly double UV strength.
- If you burn easily, cover up and use sunscreen.
Look Out Below
Snow and water can reflect the sun's rays. Skiers and swimmers should take special care. Wear sunglasses or goggles, and apply sunscreen with an SPF of at least 15. Remember to protect areas that could be exposed to UV rays by the sun's reflection, including under the chin and nose.
3 - 5: Moderate
A UV Index reading of 3 to 5 means moderate risk of harm from unprotected sun exposure.
- Take precautions, such as covering up, if you will be outside.
- Stay in shade near midday when the sun is strongest.
Me and My Shadow
An easy way to tell how much UV exposure you are getting is to look for your shadow:
- If your shadow is taller than you are (in the early morning and late afternoon), your UV exposure is likely to be low.
- If your shadow is shorter than you are (around midday), you are being exposed to high levels of UV radiation. Seek shade and protect your skin and eyes.
6 - 7: High
A UV Index reading of 6 to 7 means high risk of harm from unprotected sun exposure. Apply a sunscreen with a SPF of at least 15. Wear a wide-brim hat and sunglasses to protect your eyes.
- Protection against sunburn is needed.
- Reduce time in the sun between 10 a.m. and 4 p.m.
- Cover up, wear a hat and sunglasses, and use sunscreen.
Made in the Shades
Wearing sunglasses protects the lids of your eyes as well as the lens.
8 - 10: Very High
A UV Index reading of 8 to 10 means very high risk of harm from unprotected sun exposure. Minimize sun exposure during midday hours, from 10 a.m. to 4 p.m. Protect yourself by liberally applying a sunscreen with an SPF of at least 15. Wear protective clothing and sunglasses to protect the eyes.
- Take extra precautions. Unprotected skin will be damaged and can burn quickly.
- Minimize sun exposure between 10 a.m. and 4 p.m. Otherwise, seek shade, cover up, wear a hat and sunglasses, and use sunscreen.
Stay in the Game
Be careful during routine outdoor activities such as gardening or playing sports. Remember that UV exposure is especially strong if you are working or playing between the peak hours of 10 a.m. and 4 p.m. Don't forget that spectators, as well as participants, need to wear sunscreen and eye protection to avoid too much sun.
A UV Index reading of 11 or higher means extreme risk of harm from unprotected sun exposure. Try to avoid sun exposure during midday hours, from 10 a.m. to 4 p.m. Apply sunscreen with an SPF of at least 15 liberally every 2 hours.
- Take all precautions. Unprotected skin can burn in minutes. Beachgoers should know that white sand and other bright surfaces reflect UV and will increase UV exposure.
- Try to avoid sun exposure between 10 a.m. and 4 p.m.
- Seek shade, cover up, wear a hat and sunglasses, and use sunscreen.
Beat the Heat
It is possible to go outside when the UV Index is 11 or higher. Make sure you always seek shade, wear a hat, cover up, wear 99-100% UV-blocking sunglasses, and use sunscreen. Or you can opt to stay indoors and take the opportunity to relax with a good book rather than risk dangerous levels of sun exposure.
Chandler Burning Index Description
50 - 75
75 - 90
90 - 97.5
The Chandler Burning Index (CBI) uses the air temperature and relative humidity to calculate a numerical index of fire danger.
The CBI is based solely on weather conditions, with no adjustment for fuel moisture.
That number is then equated to an «Adjective Fire Danger Severity» of either low, moderate, high,
very high or extreme.
The modified version of the Chandler Burning Index is computed from the following formulas:
Daily CBI ratings:
Averaged 30 day historical CBI rating:
The Chandler Burning Index has been shown to be highly correlated with fire activity.
|Fire Danger Rating
and Color Code
(Light Blue or Green)
|Fuels do not ignite readily from small firebrands although a more intense heat source, such as lightning, may start fires in duff or punky wood. Fires in open cured grasslands may burn freely a few hours after rain, but woods fires spread slowly by creeping or smoldering, and burn in irregular fingers. There is little danger of spotting.|
|Fires can start from most accidental causes but, with the exception of lightning fires in some areas, the number of starts is generally low. Fires in open cured grasslands will burn briskly and spread rapidly on windy days. Timber fires spread slowly to moderately fast. The average fire is of moderate intensity, although heavy concentrations of fuel, especially draped fuel, may burn hot. Short-distance spotting may occur, but is not persistent. Fires are not likely to become serious and control is relatively easy.|
|All fine dead fuels ignite readily and fires start easily from most causes. Unattended brush and campfires are likely to escape. Fires spread rapidly and short-distance spotting is common. High-intensity burning may develop on slopes or in concentrations of fine fuels. Fires may become serious and their control difficult unless they are attacked successfully while small.|
|Very High (VH)
|Fires start easily from all causes and, immediately after ignition, spread rapidly and increase quickly in intensity. Spot fires are a constant danger. Fires burning in light fuels may quickly develop high intensity characteristics such as long-distance spotting and fire whirlwinds when they burn into heavier fuels.|
|Fires start quickly, spread furiously, and burn intensely. All fires are potentially serious. Development into high intensity burning will usually be faster and occur from smaller fires than in the very high fire danger class. Direct attack is rarely possible and may be dangerous except immediately after ignition. Fires that develop headway in heavy slash or in conifer stands may be unmanageable while the extreme burning condition lasts. Under these conditions the only effective and safe control action is on the flanks until the weather changes or the fuel supply lessens.|
Beaufort Wind Scale
Developed in 1805 by Sir Francis Beaufort of England
|Winds||WMO¹||Appearance of Wind Effects|
|Force||Knots||km/h||Classification||On Land||On the Water|
|0||< 1||< 1||Calm||Calm, smoke rises vertically||Sea surface smooth and mirror-like|
|1||1–3||1–5||Light Air||Smoke drift indicates wind direction, still wind vanes||Scaly ripples, no foam crests|
|2||4–6||6-11||Light Breeze||Wind felt on face, leaves rustle, vanes begin to move||Small wavelets, crests glassy, no breaking|
|3||7–10||12-19||Gentle Breeze||Leaves and small twigs constantly moving, light flags extended||Large wavelets, crests begin to break, scattered whitecaps|
|4||11–16||20–28||Moderate Breeze||Dust, leaves, and loose paper lifted, small tree branches move||Small waves 0.3-1.2 meters becoming longer, numerous whitecaps|
|5||17–21||29–38||Fresh Breeze||Small trees in leaf begin to sway||Moderate waves 1.2-2.4 meters taking longer form, many whitecaps, some spray|
|6||22–27||39–49||Strong Breeze||Larger tree branches moving, whistling in wires||Larger waves 2.4-4 meters, whitecaps common, more spray|
|7||28–33||50–61||Near Gale or
|Whole trees moving, resistance felt walking against wind||Sea heaps up, waves 4-6 meters, white foam streaks off breakers|
|Whole trees in motion, resistance felt walking against wind||Moderately high (4-6 meters) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks|
|9||41–47||75–88||Strong Gale||Slight structural damage occurs, slate blows off roofs||High waves (6 meters), sea begins to roll, dense streaks of foam, spray may reduce visibility|
|Seldom experienced on land, trees broken or uprooted, "considerable structural damage"||Very high waves (6-9 meters) with overhanging crests, sea white with densely blown foam, heavy rolling, lowered visibility|
|11||56–63||103–117||Violent Storm||Very rarely experienced, accompanied by widespread damage||Exceptionally high (9-14 meters) waves, foam patches cover sea, visibility more reduced|
|12||64 +||118 +||Hurricane||Devastation occurs||Air filled with foam, waves over 14 meters, sea completely white with driving spray, visibility greatly reduced|
Note 1: WMO = World Meteorological Organization
Temperature Comfort Scale
|Extreme Cold||Wind Chill less than -18°C|
|Uncomfortably Cold||Wind Chill between -18°C and -1°C|
|Cold||Wind Chill between -1°C and 15.5°C|
|Comfortable||Temperature between 15.5°C and 26.5°C|
|Warm||Temperature between 26.5°C and 32°C|
|Uncomfortably Hot||Temperature greater than 32°C and Heat Index less than 37.5°C|
|Extreme Hot||Heat Index greater than 37.5°C|