Local Fire Weather Generator

This app grabs data based on location. It will generate it’s report google weather based on GPS Location.

Belt Weather Kit How to

For the Iphone/Android App This Belt Weather Kit Guide can be an expandable button.

🌤 Belt Weather Kit Guide

Purpose

A belt weather kit is used to observe current weather conditions in the field. These observations help firefighters understand fire behavior, compare current conditions with forecasts, and communicate weather information to supervisors and adjoining resources.

Remember that field observations represent conditions at the observation site and time they were taken.

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Step 1 – Select an Observation Site

Choose a location that best represents the fuels and weather conditions affecting your assignment.

Good Observation Sites

• Representative of the surrounding fuels
• Open to normal airflow
• Similar elevation and aspect as the area of concern

Avoid

• Recently burned black
• Roads and parking areas
• Vehicles or equipment
• Buildings or camps
• Water sources
• Unusual shade or localized heat

Tip: The best observation is one that reflects the fuels you’re trying to evaluate, not simply the easiest place to stand.

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Step 2 – Prepare Your Belt Weather Kit

Before taking measurements:

• Inspect the psychrometer.
• Ensure the wet bulb wick is clean and fully saturated with clean water.
• Check that all instruments appear undamaged.
• Verify the compass and wind meter (if included) are functioning properly.

Tip: A dirty or dry wick can produce inaccurate wet bulb readings.

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Step 3 – Measure Wet and Dry Bulb Temperatures

Sling the Psychrometer

Swing the psychrometer freely for approximately 20–30 seconds or according to the manufacturer’s instructions.

Immediately after stopping:

1. Read the wet bulb temperature first.
2. Read the dry bulb temperature second.

Record

• Wet Bulb
• Dry Bulb

Tip: Read the wet bulb immediately after slinging. Delays can cause the wet bulb temperature to rise, reducing accuracy.

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Step 4 – Determine Relative Humidity

Using your belt weather kit reference tables or calculator:

• Enter the Dry Bulb temperature.
• Enter the Wet Bulb temperature.
• Determine Relative Humidity (RH).

Relative humidity indicates how much moisture is present in the air and is one of the primary weather factors affecting fine fuel moisture.

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Step 5 – Estimate Fine Dead Fuel Moisture

Using the appropriate reference tables:

• Use the measured Relative Humidity.
• Consider current temperature if required by the reference.
• Determine the estimated Fine Dead Fuel Moisture.

Why it matters

Lower fuel moisture generally allows fine fuels to ignite more easily and burn more actively.

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Step 6 – Estimate Probability of Ignition

Using the appropriate reference tables:

• Use Relative Humidity and Fine Dead Fuel Moisture as required.
• Determine the estimated Probability of Ignition.

Remember that Probability of Ignition is only one factor influencing fire behavior and should be considered together with fuels, topography, and wind.

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Step 7 – Measure Wind

Measure wind at a representative location.

Record:

• Average wind speed
• Gust speed (if observed)
• Wind direction

If winds are variable, take multiple readings and note changing conditions.

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Step 8 – Observe Sky Conditions

Record observations such as:

• Cloud cover
• Visibility
• Smoke impacts
• Precipitation
• Significant weather changes

These observations provide important context for fire behavior and future weather changes.

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Step 9 – Compare with the Forecast

Compare your field observations with the forecast.

Look for differences in:

• Temperature
• Relative Humidity
• Wind speed
• Wind direction
• Gusts

Large differences may indicate localized weather effects or changing conditions that should be communicated.

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Step 10 – Continue Monitoring

Weather conditions change throughout the operational period.

Take additional observations when:

• Conditions change noticeably.
• Winds increase or shift.
• Relative humidity changes significantly.
• Entering different fuel types or elevations.
• Requested by supervisors or the Incident Action Plan.

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Common Reminders

✓ Read the wet bulb first.

✓ Use a representative observation site.

✓ Keep the wick clean and saturated.

✓ Take wind readings away from obstructions.

✓ Compare field observations with the forecast.

✓ Record observations clearly and completely.

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Weather Factors That Most Influence Fire Behavior

• Air Temperature
• Relative Humidity
• Wind Speed
• Wind Direction
• Wind Gusts
• Fine Dead Fuel Moisture
• Probability of Ignition
• Atmospheric Stability
• Cloud Cover

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Remember

A belt weather kit provides a snapshot of current field conditions. It should be used alongside official weather forecasts, incident meteorologist briefings, agency procedures, and local observations to support operational decision-making.

If your belt weather kit does not have all the tables and charts you can download this PDF. It includes Tables from the NWCG.