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Norwalk climate
Typical historical weather for Norwalk, United States, averaged across 10 years of hourly climate data. Pick a date for a specific day.
Data last updated: 31 December 2025
Want today's actual conditions instead? See the current forecast for Norwalk. Planning a garden? See the gardening & growing season planner. Or browse the 365-day climate calendar.
Annual average
12.1°C
across all months
Warmest month
29°C
Jul average high
Coolest month
-3.3°C
Jan average low
Annual rainfall
1239mm
total per year
Norwalk is typically hottest in July and coolest in January, a swing of about 32.3°C across the year. About 29% of annual rainfall falls in the three wettest months (October is typically wettest, June driest).
Monthly averages
Average daily high/low temperature (band) and monthly rainfall (bars).
| Month | Avg high | Avg low | Rainfall | Wet days | Humidity | Wind | Cloud | Solar |
|---|---|---|---|---|---|---|---|---|
| Jan | 3.4°C · record 9.5°C–18.7°C | -3.3°C · record -17.8°C–-3.1°C | 88mm | 9 | 65% | 3.7 m/s | 58% | 2.1 kWh/m² |
| Feb | 5.4°C · record 8.1°C–22.8°C | -2.3°C · record -19.9°C–-7.5°C | 91mm | 11 | 65% | 3.6 m/s | 61% | 2.9 kWh/m² |
| Mar | 9.4°C · record 14.9°C–24.8°C | 1.1°C · record -11.9°C–-2.8°C | 103mm | 11 | 60% | 3.8 m/s | 58% | 4.1 kWh/m² |
| Apr | 14.7°C · record 18.3°C–32°C | 6°C · record -5.2°C–2°C | 109mm | 13 | 62% | 3.5 m/s | 63% | 4.9 kWh/m² |
| May | 20.3°C · record 26.3°C–33.2°C | 11.4°C · record 1.1°C–7.6°C | 105mm | 12 | 69% | 3 m/s | 66% | 5.5 kWh/m² |
| Jun | 25.7°C · record 30.9°C–36.2°C | 16.7°C · record 8.4°C–12.7°C | 84mm | 11 | 69% | 2.8 m/s | 60% | 6.2 kWh/m² |
| Jul | 29°C · record 31.6°C–35.9°C | 20.7°C · record 14.3°C–18.4°C | 123mm | 14 | 72% | 2.5 m/s | 58% | 6 kWh/m² |
| Aug | 27.5°C · record 28.9°C–34.8°C | 19.6°C · record 11.1°C–16.2°C | 99mm | 12 | 73% | 2.6 m/s | 57% | 5.3 kWh/m² |
| Sep | 23.8°C · record 28.4°C–33.9°C | 15.7°C · record 6.5°C–10.6°C | 110mm | 10 | 74% | 2.8 m/s | 57% | 4.2 kWh/m² |
| Oct | 18.2°C · record 22.6°C–32.5°C | 10°C · record -1.7°C–6.2°C | 125mm | 10 | 73% | 3.3 m/s | 54% | 3 kWh/m² |
| Nov | 11.2°C · record 17.5°C–26.5°C | 3.2°C · record -11°C–-0.5°C | 86mm | 9 | 66% | 3.5 m/s | 49% | 2.3 kWh/m² |
| Dec | 5.3°C · record 12°C–16.2°C | -1.1°C · record -14.4°C–-5.6°C | 117mm | 11 | 69% | 3.5 m/s | 60% | 1.7 kWh/m² |
"Avg high"/"Avg low" is the mean daily high/low for that month, averaged across every year on file. The "record" figure alongside it is a different statistic — the single hottest (or coldest) hour ever recorded during that month across all years — so it can sit above or below the average and does not describe the average's year-to-year spread. A "wet day" is any day with at least 1.0mm of rain.
Year to year
Annual average temperature, 2016–2025.
Across these 10 years, the annual average has moved by about +0.2°C per decade. That’s a short window for a reliable long-term climate trend — treat it as indicative, not definitive.
Annual rainfall has moved by about +47.1mm per decade over the same period.
2025 (the most recent year on file) averaged 11.6°C, below the 9-year baseline of 12.2°C by 1.7 standard deviations.
Typical extremes per year
Rainy days
133.2 days
≥1.0mm rain
Heavy rain days
14.3 days
≥20mm rain
Extreme heat days
0 days
daily high ≥40°C
Frost days
79.4 days
daily low ≤0°C
Averaged across 10 years on file. Thresholds match PastClimate's data pipeline definitions — see data & sources.
Records on file
Ranked across 10 years of data currently on file (2016–2025).
Hottest day
36.2°C
24 June 2025
2025 was 1.7 SD below the 9-year average that year
Coldest day
-19.9°C
14 February 2016
2016 was 0.55 SD above the 9-year average that year
Wettest day
77.8mm
18 December 2023
2023 was 1.4 SD above the 9-year average that year
Windiest day
8.9m/s
2 March 2018
2018 was 0.99 SD below the 9-year average that year
See the detail: Norwalk on 18 December 2023.
Nearby cities
Frequently asked questions about Norwalk's climate
What is the hottest month in Norwalk?
July is typically the warmest month in Norwalk, with an average high of 29°C. January is typically the coolest, averaging -3.3°C overnight.
How much does it rain in Norwalk?
Norwalk gets about 1239mm of rain a year on average, with roughly 29% of it falling in the three wettest months (October is typically the wettest, June the driest).
How many extremely hot or cold days does Norwalk have?
On average, Norwalk sees about 0 day(s) a year at or above 40°C and about 79.4 day(s) at or below 0°C, based on 10 years of data.
Is Norwalk getting warmer?
Across the 10 years on file (2016–2025), the annual average temperature has moved by about +0.23°C per decade. That's a short window for a reliable long-term climate trend — treat it as indicative, not definitive.
What is the hottest day on record for Norwalk?
The hottest day on file is 24 June 2025 at 36.2°C, out of 10 year(s) searched.
Data & provenance
↓ Download monthly CSVData source & coverage — ERA5 reanalysis, 2016–2025 (10 years)details
- Source
- ERA5 reanalysis, accessed via the Copernicus Climate Change Service (C3S) Climate Data Store
- Data type
- Reanalysis — a physically consistent reconstruction combining a forecast model with historical observations, not a live station reading or a forecast
- Coverage
- 2016–2025 (10 years) for United States
- Location
- Norwalk — 41.250°, -73.500°, ERA5 grid cell center, 16.6 km from requested point
- Time zone
- America/New_York
- What's shown here
- Monthly and annual averages, and dated extreme-value records, derived from an hourly base record.
- Spatial resolution
- 0.25° (~25 km) distributed grid — ERA5's native model resolution is finer; this is the publicly distributed regridded product
- Version / refreshed
- Methodology v2026.07 · data last refreshed December 31, 2025
- Limitations
- A model reconstruction, not a station observation — hyper-local extremes (a single storm cell, an urban heat pocket) can differ from a nearby gauge. See the full methodology.
- Attribution
- Generated using Copernicus Climate Change Service information
Cite this data
PastClimate (2026-07-19). Historical climate data for Norwalk, United States (41.25°N, 73.50°W), derived from ERA5 (Hersbach et al., 2023, Copernicus Climate Change Service). Retrieved from https://www.pastclimate.com/
PastClimate. (2026). Historical climate data for Norwalk, United States [Data set]. Derived from ERA5 (Copernicus Climate Change Service). Retrieved July 19, 2026, from https://www.pastclimate.com/
"Historical Climate Data for Norwalk, United States." PastClimate, derived from ERA5 (Copernicus Climate Change Service), July 19, 2026, www.pastclimate.com.
@misc{pastclimate,
author = {PastClimate},
title = {Historical climate data for Norwalk, United States},
year = {2026},
note = {Derived from ERA5 (Hersbach et al., 2023), Copernicus Climate Change Service. Accessed 2026-07-19},
url = {https://www.pastclimate.com/}
}Notice something wrong with this data? Report a data issue.