Fairfax, Iowa Weather
Prairie lightning bugs rise. Day 77 of spring. Read this microseason across nine climate regions →
Fairfax weather forecast — hour by hour, 7-day outlook, NOAA radar
- TodayJun 4Overcast39%—86°59°—
- FridayJun 5Thunderstorm69%0.44″81°63°-5°
- SaturdayJun 6Heavy Showers63%0.05″85°65°+4°
- SundayJun 7Showers46%—84°68°-1°
- MondayJun 8Showers57%0.07″81°68°-3°
- TuesdayJun 9Light Drizzle38%—82°68°+1°
- WednesdayJun 10Mostly Clear20%—91°73°+9°
Ozone at AQI 42. AQI down 29 over the last 6 hours — air quality is improving sharply. Overcast through the UV peak window (cloud cover ~75%) — afternoon ozone should stay flat.
OK No precautions needed for the general population; unusually sensitive individuals may consider limiting prolonged outdoor exertion during the projected peak around 7 AM.
What's driving it
Ozone × UV × Sky
Ozone at AQI 42. Overcast through the UV peak window (cloud cover ~75%) — afternoon ozone should stay flat.
- Present
- AQI 42
- UV peak
- 3.3 at 1 PM
- Sky at peak
- overcast
- Projected peak
- AQI 9
PM × Wind × Precip
PM2.5 at 5.3 µg/m³ (AQI 29) with a 0.91 fine-to-coarse ratio and 6 mph wind — combustion smoke trapped in calm air, not road dust.
- PM2.5/PM10
- 0.91
- Wind
- light
- Recent rain
- 0h in last 6h
- Pattern
- stagnant smoke
Trends
Seven days of AQI and PM2.5.
Hourly air-quality data from the Copernicus Atmosphere Monitoring Service, charted across the past and next several days. Dashed lines mark the AQI breakpoints at 50 (Good → Moderate) and 100 (Moderate → Unhealthy for Sensitive Groups).
A summer fog for fair, a winter fog for rain.
- Moonrise
- 4:43 AM
- Moonset
- 2:03 PM
- In sign
- ♑︎ Capricorn
Prairie lightning bugs rise
Fairfax at a glance
- Today vs. normal: 10°F below the seasonal normal for this latitude
- Last frost: April 28 (climatological average for this latitude)
- Microseason: Jun 1–5
- Planting window: Harvest spring lettuce before it bolts. Sow heat-tolerant greens.
Right now in the garden
Peak growing season
As of June 4, the growing season is at its peak — frost is months away. Continue succession-planting beans and summer squash. Start fall brassicas (broccoli, cabbage, kale) from seed indoors for transplanting in late summer.
SPC Convective Outlook
Storm Prediction Center — Fairfax
SPC has placed Fairfax in the Slight Risk category for severe thunderstorms tomorrow.
- TODAYTSTMGeneral Thunderstorms
- TOMORROWSLGTSlight Risk
- DAY 3MRGLMarginal Risk
Scattered severe storms possible. A few tornadoes, hail, and damaging wind gusts possible.
Source: NOAA / NWS Storm Prediction Center categorical convective outlook. Outlooks are re-issued multiple times per day; this page reflects the most recent SPC polygons covering the city’s coordinates.
Planting calendar
| Month | Plant | Harvest |
|---|---|---|
| January | — | — |
| February | — | — |
| March | — | — |
| April | lettuce, peas, spinach, radishes | — |
| May | lettuce, peas, spinach, radishes, tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| June | tomatoes, peppers, beans, squash | lettuce, peas, radishes |
| July | tomatoes, peppers, beans, squash | tomatoes, beans, summer squash |
| August | — | tomatoes, beans, summer squash |
| September | fall brassicas, garlic (overwinter), carrots | tomatoes, beans, summer squash |
| October | fall brassicas, garlic (overwinter), carrots | winter squash, tomatoes (last) |
| November | — | — |
| December | — | — |
A year in weather
Fairfax's warmest month is July (~73°F mean) and its coldest is January (~20°F). Rainfall peaks in June (5.6 inches) and bottoms out in January (0.9 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 20° | 0.9″ | 3 |
| February | 24° | 1.2″ | 3 |
| March | 37° | 2.0″ | 5 |
| April | 49° | 3.6″ | 7 |
| May | 60° | 4.3″ | 8 |
| June | 70° | 5.6″ | 9 |
| July | 73° | 4.4″ | 6 |
| August | 71° | 4.1″ | 6 |
| September | 63° | 3.4″ | 6 |
| October | 51° | 2.9″ | 5 |
| November | 37° | 2.0″ | 4 |
| December | 25° | 1.6″ | 4 |
Regional context
Fairfax sits within a warm-summer humid continental climate region — a cohort that shares similar temperature ranges, seasonal patterns, and growing conditions across nearby cities.
Similar climates: Des Moines, IA, Davenport, IA, Cedar Rapids, IA, Iowa City, IA, Waterloo, IA.
Frequently asked
- When does it freeze in Fairfax?
- Fairfax's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Fairfax?
- June is the wettest month with about 5.6 inches of rain on average; the city receives roughly 36 inches annually.
- What is the warmest month in Fairfax?
- July is typically warmest, averaging about 73°F.
- What is the coldest month in Fairfax?
- January is typically coldest, averaging about 20°F.
- When can I start a vegetable garden in Fairfax?
- Cool-season crops (peas, lettuce) can be sown around the last spring frost (mid-April); warm-season crops (tomatoes, peppers) wait until 1–2 weeks after.
- How many rainy days does Fairfax get?
- Fairfax averages about 67 rainy days per year.
- What hardiness zone is Fairfax?
- Fairfax's USDA hardiness zone is determined by its lowest average winter temperature; check the USDA's online lookup with the city ZIP for the current zone designation.
Climate
Fairfax, Iowa sits in a warm-summer humid continental climate zone. January means hover near 20°F while July averages 73°F — a 53°F seasonal swing.
Across the year, Fairfax receives about 36 inches of precipitation spread over roughly 67 rainy days.
The rhythm of the year is set by latitude (41.9°N), proximity to large water bodies, and elevation — all of which shape what grows here, when frost is likely, and what the weather story looks like day to day.