Temperature records for Irozaki (Shizuoka)
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Temperatures over the 3 months before and after
The gray bands show the range that the high (upper band) and the low (lower band) fell within on each day over the 30 years 1996–2025 (between the 10th and 90th percentiles, so about 80% of the 30 years fall within it). The shading between the solid and dashed lines marks days when the high was above normal (warm colors) or below normal (cool colors).
Show the values by date
| Date | Observed high | Observed low | Normal high | Normal low | Range of highs | Range of lows |
|---|---|---|---|---|---|---|
| Aug 1 | 31.2°C | 25.1°C | 28.7°C | 24.2°C | ||
| Sep 1 | 28.0°C | 23.8°C | 28.1°C | 23.5°C | ||
| Oct 1 | 27.6°C | 21.5°C | 24.2°C | 19.7°C | ||
| ― | ||||||
| Dec 1 | 15.6°C | 10.5°C | 13.3–18.6°C | 7.2–13.2°C | ||
| Jan 1 | 11.9°C | 6.6°C | 8.5–13.5°C | 3.4–9.0°C | ||
| Jan 31 | 10.7°C | 5.2°C | 8.3–13.5°C | 4.0–7.9°C |
These are statistics compiled from observations for 1996–2025 (30 years), not a weather forecast for any particular day. For the latest forecasts, see the JMA website.
― on the normal curve
Monthly normals for Irozaki
Temperature (monthly normals)
The lines show monthly normals: the upper line is the monthly mean of the daily high and the lower line the monthly mean of the daily low, and the middle line is the monthly mean temperature. Touch the point for a month to read its values. Normals are the 1991–2020 average.
Precipitation (monthly normals, mm)
Table of monthly normals
| Month | Mean | High | Low | Precipitation |
|---|---|---|---|---|
| Jan | 8.2 | 11.0 | 5.7 | 67.7 |
| Feb | 8.5 | 11.5 | 5.7 | 92.4 |
| Mar | 11.0 | 14.0 | 8.1 | 147.5 |
| Apr | 14.9 | 17.9 | 12.1 | 152.2 |
| May | 18.4 | 21.2 | 16.0 | 176.9 |
| Jun | 21.1 | 23.6 | 19.1 | 236.8 |
| Jul | 24.5 | 27.0 | 22.7 | 203.3 |
| Aug | 26.2 | 28.8 | 24.3 | 124.9 |
| Sep | 23.9 | 26.3 | 21.8 | 186.4 |
| Oct | 19.7 | 22.1 | 17.5 | 193.8 |
| Nov | 15.4 | 17.9 | 13.0 | 126.6 |
| Dec | 10.8 | 13.4 | 8.3 | 72.7 |
Temperatures are in degrees Celsius (°C) and precipitation in mm. Blank cells have no normal.
Annual mean temperature (1996–2025)
The yearly average of the daily mean temperature (the line is broken in years with many missing values). This station's observing conditions changed on December 4, 2007; June 25, 2008; December 12, 2013 (for example, a relocation or new instruments), so the statistics may not be continuous across those dates.
The normals listed here are averages over the 30 years from 1991 to 2020. They are fixed values that stay the same until the next revision of the normals, and they show how warm or cold that month usually is in that area.
All-time records
Records are statistics as of November 1, 2026. The statistical period differs by element, depending on when observations began or the station moved.
| Record | Value | Date | Records began |
|---|---|---|---|
| Highest temperature | 33.9°C | Jul 20, 2004 | Jun 1939 |
| Lowest temperature | -2.7°C | Feb 26, 1981 | Jun 1939 |
| Highest daily minimum | 28.8°C | Aug 19, 2024 | Jun 1939 |
| Lowest daily maximum | 1.7°C | Feb 26, 1981 | Jun 1939 |
| Heaviest daily rainfall | 290.0 mm | Sep 29, 1970 | Jun 1939 |
Top 5 highest temperatures
| Rank | Value | Date |
|---|---|---|
| 1 | 33.9°C | Jul 20, 2004 |
| 2 | 33.8°C | Aug 14, 2024 |
| 3 | 33.6°C | Aug 16, 2020 |
| 4 | 33.4°C | Aug 4, 1990 |
| 5 | 33.3°C | Aug 26, 2025 |
12-month dry-day calendar
The dry-day rate is the share of years with no precipitation (rain or snow) of 1 mm or more on that day (daily precipitation under 1 mm, smoothed over 4 days either side). It is based on observations for 1996–2025 (30 years).
The deeper the amber, the more years that day stayed dry (the legend above shows the colors). Each row ends with the monthly average; detailed values are in the monthly table below.
Monthly averages through the year
How the monthly average dry-day rate changes over the 12 months (the axis fits the range of values). The values match the monthly table below.
Monthly table of dry-day rates and climate
| Month | Dry-day rate | 2 days in a row | 3 days in a row | Windy days | Sunshine (avg.) | High (avg.) | Low (avg.) | Comfort |
|---|---|---|---|---|---|---|---|---|
| Jan | 81.1% | 68.3% | 56.8% | 49.7% | 5.9 h | 11.0°C | 5.7°C | Fair |
| Feb | 74.8% | 57.8% | 44.5% | 46.6% | 6.0 h | 11.6°C | 5.8°C | Fair |
| Mar | 67.4% | 47.7% | 32.5% | 48.3% | 6.2 h | 14.5°C | 8.4°C | Good |
| Apr | 67.4% | 48.8% | 35.1% | 45.0% | 6.5 h | 18.0°C | 12.3°C | Comfortable |
| May | 65.9% | 47.5% | 33.3% | 33.1% | 6.3 h | 21.4°C | 16.1°C | Comfortable |
| Jun | 59.3% | 40.2% | 27.2% | 26.3% | 4.8 h | 23.9°C | 19.4°C | Good |
| Jul | 69.2% | 54.4% | 45.3% | 23.4% | 5.8 h | 27.4°C | 23.0°C | Good |
| Aug | 76.4% | 64.0% | 53.6% | 29.2% | 7.3 h | 29.2°C | 24.6°C | Fair |
| Sep | 65.1% | 49.0% | 36.8% | 37.8% | 6.2 h | 26.7°C | 22.1°C | Good |
| Oct | 68.8% | 51.8% | 38.6% | 40.2% | 5.3 h | 22.2°C | 17.6°C | Comfortable |
| Nov | 72.0% | 54.6% | 40.9% | 36.2% | 5.4 h | 18.0°C | 13.2°C | Comfortable |
| Dec | 79.1% | 65.1% | 53.9% | 50.5% | 6.0 h | 13.4°C | 8.3°C | Good |
"2 days in a row" and "3 days in a row" are the monthly averages of the share of years in which it stayed dry for 2 or 3 days from that day (counted from the actual consecutive records). "Windy days" is the share of days with a daily mean wind speed of 5 m/s or more. Sunshine averages include estimates from March 2021 onward at some stations. The month names link to monthly pages that compare stations across Japan.
Comfort over the 12 months
A guide that rates the comfort of each month on 5 levels from observations of dry-day rate, sunshine, wind, and temperature for 1996–2025 (30 years). The levels are also in the monthly table above.
This station's observing conditions changed on December 4, 2007; June 25, 2008; December 12, 2013 (for example, a relocation or new instruments), so the statistics may not be continuous across those dates.
These are statistics compiled from observations for 1996–2025 (30 years), not a weather forecast for any particular day. For the latest forecasts, see the JMA website.
About the Irozaki station
This staffed weather station is at an elevation of 52 m on a point jutting into the sea at the southern tip of the Izu Peninsula, and its statistics run from June 1939. The record high is 33.9°C on July 20, 2004, 7.5°C below the 41.4°C at Shizuoka, also in Shizuoka Prefecture. That July 20 was also the day Omaezaki set its record of 36.7°C.
In winter, too, the sea props up temperatures: even on January 26, when the normal minimum is lowest, it is 5.2°C, and the record low is -2.7°C on February 26, 1981. On the same day the daytime high reached only 1.7°C, which also stands as the lowest daily maximum on record. The gap between the normal maximum of 29.0°C on August 7, the warmest day in the normals, and 10.7°C on January 18, the coldest day in the normals, is 18.3°C.
Record values in this description are based on data collected as of September 2026.
Compare and explore
Nearby stations: Matsuzaki (about 18 km) / Inatori (about 27 km) / Niijima Island (about 47 km)
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Stations in Shizuoka / Today's national rankings / Trip planning calendar / Pressure changes at Irozaki