Lannon, WI climate
Lannon has cold, snowy winters and pleasant summers. A typical July afternoon reaches 82°, a January night drops to 13°, and about 54 inches of snow falls in a normal winter.
NOAA 1991-2020 climate normals Updated once a decadeWhat a year in Lannon feels like
Winter
Spring
Summer
Fall
Lannon weather by month
Average highs, lows, rain and snow for every month, from NOAA’s 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 28° | 13° | 1.6" | 16.5" | 10 | 23 | 10° – 32° |
| February | 32° | 16° | 1.5" | 16.0" | 8 | 19 | 12° – 34° |
| March | 43° | 25° | 2.0" | 6.5" | 9 | 9 | 26° – 48° |
| April | 55° | 35° | 3.7" | 2.0" | 11 | 1 | 36° – 51° |
| May | 68° | 45° | 3.9" | 0.3" | 13 | 0 | 50° – 62° |
| June | 77° | 56° | 4.6" | 0 | 12 | 0 | 62° – 71° |
| July | 82° | 60° | 3.7" | 0 | 11 | 0 | 66° – 78° |
| August | 80° | 59° | 3.8" | 0 | 11 | 0 | 64° – 75° |
| September | 73° | 51° | 3.2" | 0 | 10 | 0 | 56° – 67° |
| October | 60° | 40° | 2.8" | 0.3" | 12 | 0 | 46° – 56° |
| November | 45° | 29° | 2.1" | 2.4" | 10 | 3 | 28° – 46° |
| December | 33° | 19° | 1.8" | 10.3" | 9 | 15 | 14° – 36° |
| Year | 56° | 37° | 34.7" | 54.3" | 125 | 70 |
“Wet days” have at least 0.01" of rain or melted snow. “Snow on ground” counts days with 1" or more. The 30-year range is the coldest and warmest that month’s average temperature got between 1991 and 2020.
Rain and snow in Lannon
Lannon gets 35 inches of rain and melted snow a year. June is the wettest month and February the driest. Rain or snow falls on about 125 days a year. Snow covers the ground about 70 days of the year.
About 154 frost-free days a year
In half of years the last 32° night comes by May 6 and the first one by October 8. That leaves about 154 frost-free days for gardens, shorter than 77% of U.S. towns.
Heating and cooling a home in Lannon
Engineers use “degree days” to estimate how hard a furnace or air conditioner works. In Lannon, 94% of that work is heating and 6% is cooling, so the furnace matters far more than the air conditioner.
Degree days measure how far each day’s average temperature falls below or rises above 65°, added up over a year. Source: NOAA station normals.
Lannon and its neighbors
Lannon borders 2 towns with climate data. January nights across them vary by 1.3°. Lisbon has the coldest January nights (12°) and Menomonee Falls the hottest July afternoons (82°). Lannon’s January low is 13° and its July high 82°.
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value.
How Lannon compares
Compared with every U.S. town and city on TownTapestry, each counted once.
Warmer than it used to be
The last 30 years in Lannon averaged 1.4° warmer than the 1900s. The biggest change is in December (+3.1°). The shift is larger than in 62% of U.S. towns.
Change by month1991–2020 average minus 1901–2000 average, at Lannon’s spot on NOAA’s grid
How much a month can swing
A normal is an average, and real years wander around it. March swings the most: between 1991 and 2020 its average temperature ranged from 26° to 48°. June is the most reliable, staying within 9°.
Common questions about Lannon’s climate
What is the coldest month in Lannon?
January, with a typical high of 28° and a low of 13°.
What is the hottest month in Lannon?
July, with a typical high of 82° and a low of 60°. About 7 days a year reach 90°.
How much snow does Lannon get?
About 54 inches in a normal winter, most of it in January.
When is the first frost in Lannon?
In half of years the first 32° night comes by October 8, and the last spring frost by May 6.
What is the rainiest month in Lannon?
June, with 4.6 inches of rain and melted snow. The year totals 35 inches.
Temperatures and rainfall come from NOAA’s gridded climate normals for Lannon itself (about a 3-mile square). Snow, frost dates and day counts come from NOAA’s weather station at Germantown, WI (6 mi) away. Normals are 30-year averages, not a forecast. Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000.