United States · 1991–2020

Best time to visit
Carterville.

September leads for comfortable weather in Carterville: typically 27.4°C by day, 13.4°C at night, with 79 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high27.4°C

Typical low13.4°C

Rain in September79 mm

Comfort

September

September · May · October

77climate match

Beach

July

July · August · June

74climate match

Outdoors

October

October · April · September

76climate match

The weakest month is January, scoring 5 against September’s 77 — days reach only 5.3°C, 19° below the 24°C the score treats as ideal.

Month by month

The whole year,
without the guesswork.

The bars show the comfort score. Day and night temperatures come from daily observed highs and lows; rain is the historical monthly estimate.

Jan

55.3° / -4.8°

Feb

58° / -3.1°

Mar

2313.5° / 1.4°

Apr

5119.9° / 6.9°

May

7324.8° / 12.8°

Jun

6129.5° / 17.8°

Jul

5431.2° / 19.8°

Aug

6130.8° / 18.1°

Sep

7727.4° / 13.4°

Oct

6421.1° / 6.8°

Nov

2613.5° / 1.5°

Dec

57.5° / -2.6°

Monthly climate evidence for Carterville — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	5.3°C	-4.8°C	84 mm	7.3	9 h 49	5	Strong coverage
February	8°C	-3.1°C	79 mm	7.1	10 h 44	5	Strong coverage
March	13.5°C	1.4°C	117 mm	9.7	11 h 50	23	Strong coverage
April	19.9°C	6.9°C	140 mm	10.1	13 h 07	51	Strong coverage
May	24.8°C	12.8°C	134 mm	10.2	14 h 11	73	Strong coverage
June	29.5°C	17.8°C	116 mm	8.3	14 h 46	61	Strong coverage
July	31.2°C	19.8°C	102 mm	7	14 h 32	54	Strong coverage
August	30.8°C	18.1°C	88 mm	7	13 h 37	61	Strong coverage
September	27.4°C	13.4°C	79 mm	6.2	12 h 23	77	Strong coverage
October	21.1°C	6.8°C	94 mm	7	11 h 09	64	Strong coverage
November	13.5°C	1.5°C	114 mm	7.9	10 h 05	26	Strong coverage
December	7.5°C	-2.6°C	95 mm	8.1	9 h 34	5	Strong coverage

What has changed

Carterville runs +0.1°C
on the 1961–1990 baseline.

Each bar compares the 2011–2025 daytime average for that month against the same month in 1961–1990, measured at the same station. Months where the older record is too thin to compare are left blank.

Jan

+0.5

Feb

+0.4

Mar

+0.8

Apr

-0.3

May

-0.5

Jun

-0.1

Jul

-0.4

Aug

-1.0

Sep

+0.4

Oct

+0.1

Nov

-0.4

Dec

+1.9

September daytime highs, 2011–2025. Last recorded: 29.1°C.

Records at CARBONDALE SEWAGE PLT, 1898–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	24.4°C24 Jan 1943	-31.7°C11 Jan 1977	121 mm14 Jan 1937	435 mm1950 · driest 3 mm in 1943	119
February	26.1°C24 Feb 1982	-30.0°C2 Feb 1951	95 mm6 Feb 2008	220 mm2008 · driest 11 mm in 2017	119
March	33.9°C23 Mar 1910	-23.9°C5 Mar 1978	155 mm19 Mar 2008	305 mm1945 · driest 2 mm in 1910	120
April	33.3°C28 Apr 1915	-6.7°C1 Apr 1954	132 mm29 Apr 2017	377 mm2011 · driest 20 mm in 1915	121
May	38.3°C28 May 1911	-1.7°C1 May 1903	147 mm22 May 1957	320 mm1957 · driest 10 mm in 2012	118
June	42.2°C30 Jun 2012	3.9°C16 Jun 1917	175 mm17 Jun 2000	405 mm1935 · driest 6 mm in 1933	122
July	44.4°C24 Jul 1934	5.6°C6 Jul 1972	146 mm11 Jul 2026	344 mm1958 · driest 2 mm in 1901	122
August	45.0°C9 Aug 1930	5.0°C31 Aug 1915	128 mm17 Aug 1959	284 mm1932 · driest 0 mm in 2025	119
September	42.2°C4 Sep 1925	-6.7°C30 Sep 1899	107 mm12 Sep 1988	242 mm1993 · driest 2 mm in 1928	121
October	35.6°C3 Oct 1922	-8.9°C29 Oct 1952	112 mm4 Oct 1910	261 mm1910 · driest 0 mm in 1964	118
November	31.1°C1 Nov 1933	-18.3°C30 Nov 1929	136 mm20 Nov 1991	243 mm1921 · driest 6 mm in 1910	121
December	25.0°C3 Dec 1982	-25.6°C22 Dec 1989	91 mm3 Dec 1982	311 mm1982 · driest 7 mm in 1955	117

Typical days per month at CARBONDALE SEWAGE PLT, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	25	3	2
February	0	0	21	3	2
March	1	0	14	4	<1
April	6	<1	3	4	0
May	17	4	0	5	0
June	27	15	0	4	0
July	30	22	0	3	0
August	30	20	0	3	0
September	22	10	<1	3	0
October	9	1	4	3	<1
November	<1	0	14	3	<1
December	0	0	22	3	2

The best month has moved. On the 1961–1990 numbers the strongest month here was September (scoring 80); on 2011–2025 it is May (81). Both are scored the same way, from the same station — only the climate underneath changed.

How often, not how much — every day in CARBONDALE SEWAGE PLT’s record sorted by what it was actually like, rather than averaged
Month	Warm & dry days	Wet days	Washouts	Week with 3+ wet days	Daytime mean has ranged
January	<1%	24%	9%	24%	2.5–9.6°C
February	4%	24%	9%	24%	4.3–11.8°C
March	16%	29%	12%	35%	10.0–17.8°C
April	39%	31%	12%	38%	18.1–22.7°C
May	62%	32%	13%	39%	23.0–27.9°C
June	73%	26%	12%	29%	28.0–32.6°C
July	77%	23%	10%	21%	30.3–34.8°C
August	77%	23%	10%	23%	29.0–34.2°C
September	76%	21%	9%	20%	25.6–31.0°C
October	55%	20%	8%	21%	19.7–24.6°C
November	16%	25%	10%	25%	11.1–16.9°C
December	2%	25%	9%	27%	5.1–11.0°C

A warm and dry day reaches 20°C with under 1 mm of rain; a wet day gets 1 mm or more; a washout gets 10 mm or more. The week column is the share of seven-day stretches in that month, across the station’s whole daily record, that contained three or more wet days — the odds a week-long trip is rained on repeatedly, counted rather than modelled. The last column is the 10th to 90th percentile of that month’s daytime average across individual years: a narrow band means the average is what you will get, a wide one means the average is a midpoint between years that felt quite different.

1900Each stripe is one year’s mean temperature against the 108-year average. Warmest: 1921. Coolest: 1979.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4235311
NOAA station: USC00111265 · CARBONDALE SEWAGE PLT
Station distance: 8.4 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 29 usable years
Daylight: Calculated from latitude 37.76°, mid-month, sunrise to sunset including refraction. Not a station measurement.
Important limit: Historical climate is not a forecast. Nearby stations can miss mountains, coasts, and local microclimates.

These places read the same station, so their numbers are identical — distance from CARBONDALE SEWAGE PLT is what differs

Carbondale→Marion→Herrin→Johnston City→Crainville→Cambria→

Or put two places side by side: Carterville vs Carbondale

Best time to visitCarterville.