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City briefing

Johnston

Iowa, United States · 23,000 people
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
The year’s records
Annual mean 11°C · wettest around May · prevailing wind SW
Warmest
27.7 °C
Coldest
-4.9 °C
Wettest
52%
Windiest
6.7 m/s
Prevailing
SW
5.0 m/s average

When this place is good five ratings · thirty-six ten-day sections · click a cell to read it

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
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Nov
Dec

Every reading

bars actual · line feels-like, °C
-15-10-5051015202530JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember-15-10-5051015202530JFMAMJJASOND

The average temperature in Johnston over the whole year is 11°C. July is the hottest month, with highs of about 28°C; January is the coldest, with lows of about -7°C.

Month by month Johnston climate by month: average temperatures year round · click a month to read it

MonthHighLowFeels likeChance of rainCloudWindBeing outsideSunWalking
January-4°C-7°C-10°C47%58%4.4 m/s001
February-0°C-6°C-7°C46%48%4.4 m/s109
March7°C1°C1°C50%54%4.8 m/s4023
April14°C5°C7°C51%50%5.1 m/s21047
May20°C13°C17°C53%48%4.0 m/s561264
June27°C19°C26°C51%33%3.6 m/s545326
July28°C20°C28°C49%32%2.8 m/s416213
August27°C18°C27°C50%35%2.8 m/s535324
September24°C15°C23°C51%35%3.1 m/s643844
October16°C8°C11°C50%43%3.8 m/s34358
November8°C1°C2°C48%44%4.2 m/s7026
December1°C-4°C-5°C48%51%4.3 m/s007

High and low are the warmest and coolest of four readings a day — midnight, 6am, noon and 6pm — so a true overnight low can sit a degree or two under them. Chance of rain, cloud and wind are the day’s average; feels-like and the three ratings (each out of 100: Good from 55, Ideal from 80) are read at midday.

Seasons, and the year in short Johnston weather by season

Year round, Johnston has days of about -4°C at their warmest in January, its coolest month, and 28°C in July, its warmest; the coolest hours of the day run from -7°C to 20°C through the year, and the average temperature over the year is 11°C around the clock. Rain is most likely around May and least likely around February. Every figure here is a decade of observations blended into one representative year, so it reads as what this date is usually like, not a forecast for one particular day.

Johnston weather in winterDecember to February

High -1°CLow -6°CRain 47%

Winter in Johnston has typical daily highs of about -1°C and lows of about -6°C, with a 47% chance of rain on a given day.

Johnston weather in springMarch to May

High 14°CLow 6°CRain 51%

Spring in Johnston has typical daily highs of about 14°C and lows of about 6°C, with a 51% chance of rain on a given day.

Johnston weather in summerJune to August

High 27°CLow 19°CRain 50%

Summer in Johnston has typical daily highs of about 27°C and lows of about 19°C, with a 50% chance of rain on a given day.

Johnston weather in autumnSeptember to November

High 16°CLow 8°CRain 50%

Autumn in Johnston has typical daily highs of about 16°C and lows of about 8°C, with a 50% chance of rain on a given day.

When is the rainy season in Johnston?

Johnston has no sharply defined rainy season: the chance of rain on a given day runs from 46% in February, the driest month, to 53% in May, the wettest.

What time of year is Johnston windiest?

Winds in Johnston are highest in April, averaging 5.1 m/s (18 km/h), and lightest in July, at 2.8 m/s (10 km/h). The prevailing wind is from the SW.

What is the average temperature in Johnston year round?

The average temperature in Johnston over the whole year is 11°C. July is the hottest month, with highs of about 28°C; January is the coldest, with lows of about -7°C.

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