United States · 1991–2020

Best time to visit
Princeton.

September leads for comfortable weather in Princeton: typically 27.3°C by day, 14.1°C at night, with 104 mm of rain. Based on measured 1991–2020 NOAA station history.

Best comfortSeptember

Typical high27.3°C

Typical low14.1°C

Rain in September104 mm

Comfort

September

September · May · October

74climate match

Beach

July

July · June · August

73climate match

Outdoors

October

October · April · March

82climate match

The weakest month is January, scoring 5 against September’s 74 — days reach only 5°C, 19° below the 24°C the score treats as ideal, and nights drop to -6.3°C.

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° / -6.3°

Feb

107.9° / -4.4°

Mar

3614.1° / 1.2°

Apr

5819.7° / 6.6°

May

7124.5° / 12.5°

Jun

5829.5° / 17.9°

Jul

5132.2° / 20.3°

Aug

5231.7° / 19.1°

Sep

7427.3° / 14.1°

Oct

6720.8° / 7.4°

Nov

3313.1° / 1°

Dec

66.8° / -4.2°

Monthly climate evidence for Princeton — daylight is calculated from latitude, everything else is measured
Month	Day	Night	Rain	Wet days	Daylight	Comfort	Coverage
January	5°C	-6.3°C	31 mm	4.6	9 h 45	5	Strong coverage
February	7.9°C	-4.4°C	41 mm	4.9	10 h 42	10	Strong coverage
March	14.1°C	1.2°C	58 mm	6.4	11 h 50	36	Strong coverage
April	19.7°C	6.6°C	96 mm	7.9	13 h 09	58	Strong coverage
May	24.5°C	12.5°C	148 mm	10.4	14 h 14	71	Strong coverage
June	29.5°C	17.9°C	132 mm	8.2	14 h 50	58	Strong coverage
July	32.2°C	20.3°C	95 mm	7.4	14 h 36	51	Strong coverage
August	31.7°C	19.1°C	117 mm	7.5	13 h 39	52	Strong coverage
September	27.3°C	14.1°C	104 mm	6.8	12 h 23	74	Strong coverage
October	20.8°C	7.4°C	77 mm	6.5	11 h 08	67	Strong coverage
November	13.1°C	1°C	60 mm	5	10 h 02	33	Strong coverage
December	6.8°C	-4.2°C	43 mm	4.5	9 h 30	6	Strong coverage

What has changed

Princeton runs -0.3°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

+0.3

Feb

-0.6

Mar

+0.2

Apr

-1.5

May

-1.4

Jun

+0.2

Jul

-0.8

Aug

-1.1

Sep

+0.3

Oct

-0.6

Nov

-0.1

Dec

+1.5

September daytime highs, 2011–2025. Last recorded: 27.2°C.

Records at OTTAWA, 1895–2026
Month	Record high	Record low	Wettest day	Wettest / driest month	Years
January	24.4°C24 Jan 1950	-28.9°C4 Jan 1947	66 mm30 Jan 1982	137 mm1941 · driest 0 mm in 1986	131
February	28.9°C25 Feb 1981	-33.3°C13 Feb 1905	73 mm21 Feb 1997	122 mm1911 · driest 1 mm in 2006	130
March	34.4°C27 Mar 2026	-22.8°C12 Mar 1948	65 mm30 Mar 1980	258 mm1973 · driest 4 mm in 1910	131
April	35.6°C29 Apr 1910	-11.7°C5 Apr 1920	109 mm22 Apr 1944	263 mm1944 · driest 14 mm in 2000	131
May	38.3°C31 May 2000	-6.1°C4 May 1907	103 mm16 May 1898	389 mm2019 · driest 36 mm in 1980	130
June	42.2°C27 Jun 1980	4.4°C4 Jun 1897	139 mm9 Jun 1984	327 mm1965 · driest 7 mm in 1936	131
July	47.8°C14 Jul 1954	8.3°C31 Jul 1971	147 mm7 Jul 1909	350 mm1951 · driest 0 mm in 1936	131
August	45.0°C14 Aug 1936	5.6°C27 Aug 1910	215 mm1 Aug 2019	465 mm2019 · driest 7 mm in 1984	131
September	43.9°C3 Sep 1947	-2.8°C29 Sep 1908	161 mm13 Sep 1961	335 mm1961 · driest 5 mm in 1939	131
October	36.7°C7 Oct 1939	-8.9°C30 Oct 1925	146 mm25 Oct 2023	278 mm1941 · driest 0 mm in 1952	131
November	30.0°C8 Nov 1980	-17.2°C16 Nov 1932	177 mm16 Nov 1928	273 mm1928 · driest 0 mm in 1954	131
December	23.9°C6 Dec 1939	-30.0°C23 Dec 1989	52 mm15 Dec 1971	119 mm1947 · driest 0 mm in 1979	129

Typical days per month at OTTAWA, 1991–2020
Month	Days 25°C+	Days 30°C+	Frost nights	Heavy rain (10 mm+)	Snow days
January	0	0	26	<1	3
February	<1	0	22	1	2
March	2	<1	14	2	<1
April	7	<1	4	3	0
May	16	4	<1	5	0
June	27	16	0	4	0
July	30	24	0	3	0
August	29	22	0	3	0
September	21	10	0	3	0
October	9	2	3	2	<1
November	<1	0	14	2	<1
December	0	0	24	2	2

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

How often, not how much — every day in OTTAWA’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%	14%	3%	10%	0.2–8.4°C
February	5%	16%	4%	11%	3.0–11.7°C
March	21%	21%	8%	20%	9.7–17.7°C
April	43%	26%	10%	29%	17.1–22.2°C
May	60%	32%	14%	40%	22.0–27.1°C
June	70%	29%	14%	34%	27.5–31.7°C
July	78%	23%	9%	22%	29.9–34.9°C
August	77%	23%	10%	24%	29.4–35.0°C
September	74%	23%	11%	23%	25.3–30.7°C
October	56%	19%	8%	19%	19.0–23.7°C
November	17%	15%	6%	11%	9.9–16.2°C
December	2%	15%	4%	10%	3.0–9.7°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.

1897Each stripe is one year’s mean temperature against the 123-year average. Warmest: 1954. Coolest: 2014.2025

The evidence behind this page

Nearby, measured,
and named.

Place identity: GeoNames 4277762
NOAA station: USC00146128 · OTTAWA
Station distance: 13.8 km from the place centre
Climate period: 1991–2020
Minimum month coverage: 29 usable years
Daylight: Calculated from latitude 38.49°, 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 OTTAWA is what differs

Ottawa→Baldwin City→Rantoul→B N Junction→Centropolis→Homewood→

Or put two places side by side: Princeton vs Ottawa

Best time to visitPrinceton.