| Month | Temp. (min) | Temp. (max) | Temp. (avg) | Precipitation |
| January | 12°F | 31°F | 21°F | 1.6" |
| February | 17°F | 38°F | 27°F | 1.3" |
| March | 27°F | 51°F | 38°F | 1.8" |
| April | 33°F | 61°F | 46°F | 2.3" |
| May | 39°F | 70°F | 54°F | 2.3" |
| June | 46°F | 83°F | 65°F | 1.2" |
| July | 54°F | 93°F | 74°F | 0.5" |
| August | 51°F | 90°F | 71°F | 0.8" |
| September | 43°F | 80°F | 60°F | 1.5" |
| October | 33°F | 64°F | 47°F | 1.5" |
| November | 25°F | 49°F | 36°F | 1.2" |
| December | 16°F | 34°F | 25°F | 1.2" |
| Index | Smithfield | Utah | National |
| Air quality index | 44 | 45 | 42 |
| Pollution index | 2,422,660 | 3,340,369 | 2,726,193 |
| Measurement | Total |
| Days measured | 365 |
| Days with good air quality | 272 |
| Days with moderate air quality | 79 |
| Days w/ poor A.Q. for sensitive groups | 14 |
| Days with unhealthy air quality | 0 |
| Pollutant | Total |
| Arsenic | 0.001% |
| Benzene | 0.040% |
| Carbon Tetrachloride | 0.000% |
| Lead | 0.050% |
| Mercury | 0.001% |
| City | Population | Air Quality Index | National Avg. |
| Weston, ID | 440 | 44 | 12.0% |
| Deweyville, UT | 370 | 44 | 12.0% |
| Newton, UT | 800 | 44 | 12.0% |
| Hyde Park, UT | 4,703 | 44 | 12.0% |
| Millville, UT | 1,895 | 44 | 12.0% |
| Smithfield, UT | 11,670 | 44 | 12.0% |
| City | Population | Air Quality Index | National Avg. |
| Estevan, SK | 11,667 | n/a | |
| Dent, OH | 11,675 | 54 | 8.0% |
| Cocoa Beach, FL | 11,663 | 36 | 28.0% |
| Martensville, SK | 11,678 | n/a | |
| Emeryville, CA | 11,679 | 40 | 20.0% |
| Smithfield, UT | 11,670 | 44 | 12.0% |
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