Weather in Waterloo, California
Fog and sun in daily rhythm. Day 58 of spring. Read this microseason across nine climate regions →
- TodayMay 16Overcast—80°54°
- SundayMay 17Overcast—75°53°
- MondayMay 18Clear—84°57°
- TuesdayMay 19Clear—90°55°
- WednesdayMay 20Overcast—94°60°
- ThursdayMay 21Overcast—96°60°
- FridayMay 22Partly Cloudy—93°58°
- PM 2.5
- 7.1 μg/m³
- PM 10
- 61.0 μg/m³
- NO₂
- 0.8 μg/m³
- Ozone
- 115.0 μg/m³
- UV Index
- 3.8 Moderate
Flowers blooming in late autumn, a sure sign of a bad winter coming.
- Moonrise
- 12:20 PM
- Moonset
- 2:27 AM
- In sign
- ♉︎ Taurus
Fog and sun in daily rhythm
Waterloo at a glance
- Today vs. normal: 5°F above the seasonal normal for this latitude
- Last frost: April 4 (climatological average for this latitude)
- Microseason: 28 of 72, May 16–20
- Planting window: Direct sow okra, melons, and southern peas. Thin carrot rows.
Right now in the garden
Warm-season window is open
As of May 16, the last spring frost has passed for most years. Transplant tomatoes, peppers, eggplants, basil, and cucurbits (cucumbers, squash, melons) now. Direct-sow beans and corn into warm soil.
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
Waterloo's warmest month is July (~78°F mean) and its coldest is January (~49°F). Rainfall peaks in January (3.6 inches) and bottoms out in July (0.0 inches).
| Month | Mean temp | Precip | Rainy days |
|---|---|---|---|
| January | 49° | 3.6″ | 8 |
| February | 53° | 3.1″ | 7 |
| March | 58° | 2.4″ | 6 |
| April | 62° | 1.4″ | 3 |
| May | 69° | 0.6″ | 2 |
| June | 74° | 0.1″ | 0 |
| July | 78° | 0.0″ | 0 |
| August | 77° | 0.0″ | 0 |
| September | 75° | 0.1″ | 0 |
| October | 66° | 1.0″ | 2 |
| November | 56° | 1.8″ | 4 |
| December | 49° | 3.1″ | 7 |
Frequently asked
- When does it freeze in Waterloo?
- Waterloo's last spring frost typically falls around mid-April, and the first fall frost arrives around mid-November.
- What is the rainy season in Waterloo?
- January is the wettest month with about 3.6 inches of rain on average; the city receives roughly 17 inches annually.
- What is the warmest month in Waterloo?
- July is typically warmest, averaging about 78°F.
- What is the coldest month in Waterloo?
- January is typically coldest, averaging about 49°F.
- When can I start a vegetable garden in Waterloo?
- 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 Waterloo get?
- Waterloo averages about 39 rainy days per year.
- What hardiness zone is Waterloo?
- Waterloo'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
Waterloo, California sits in a hot-summer Mediterranean climate zone. January means hover near 49°F while July averages 78°F — a 29°F seasonal swing.
Across the year, Waterloo receives about 17 inches of precipitation spread over roughly 39 rainy days.
The rhythm of the year is set by latitude (38.0°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.