Nipigon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Nipigon clear sky chart from 2005-11-06 to 2026-07-01.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	13% 10% 4 8% 5% 5% 5% 4 6% 7% 34%	138036
	Night	13% 11% 4 10% 6% 5% 5% 4 6% 7% 29%	134657
Transparency	Day	31% 37% 9% 15% 7% 1	141427
	Night	36% 37% 8% 13% 5% 1	139339
Seeing	Day	18% 17% 35% 20% 7% 2	18080
	Night	19% 11% 31% 29% 10% 1	27646

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	8% 14% 6% 12% 7% 8% 7% 5% 7% 8% 18%	4691
	11th to 20th	Day	6% 13% 6% 14% 6% 8% 7% 7% 9% 8% 15%	4679
	21st to end	Day	7% 13% 7% 10% 7% 7% 7% 5% 8% 8% 21%	5156
February	1st to 10th	Day	8% 12% 4 10% 6% 4 7% 6% 7% 8% 29%	1706
	11th to 20th	Day	7% 11% 5% 11% 7% 4 4 4 7% 7% 32%	1897
	21st to end	Day	6% 11% 4 10% 8% 7% 5% 4 7% 8% 30%	1730
March	1st to 10th	Day	11% 11% 4 9% 6% 5% 6% 4 6% 6% 33%	4578
	11th to 20th	Day	9% 12% 5% 11% 6% 7% 5% 4 5% 5% 31%	4772
	21st to end	Day	18% 14% 3 8% 4 4 4 3 4 5% 32%	6101
April	1st to 10th	Day	14% 12% 3 8% 5% 5% 5% 4 5% 6% 34%	2520
	11th to 20th	Day	17% 11% 4 8% 5% 5% 4 4 6% 7% 29%	2550
	21st to end	Day	17% 11% 3 7% 4 4 5% 3 6% 6% 34%	2772
May	1st to 10th	Day	13% 9% 3 7% 5% 4 4 3 6% 7% 38%	8241
	11th to 20th	Day	18% 8% 3 6% 4 4 3 3 4 6% 40%	8222
	21st to end	Day	11% 6% 2 5% 4 4 4 4 6% 8% 47%	9234
June	1st to 10th	Day	18% 7% 3 6% 4 4 5% 4 6% 8% 36%	3150
	11th to 20th	Day	14% 7% 3 6% 4 4 5% 4 6% 8% 38%	3150
	21st to end	Day	17% 7% 2 7% 5% 5% 4 3 6% 7% 37%	3150
July	1st to 10th	Day	12% 5% 2 5% 3 4 4 4 6% 8% 46%	6547
	11th to 20th	Day	11% 5% 2 6% 5% 4 5% 4 6% 8% 44%	6360
	21st to end	Day	12% 5% 2 5% 4 5% 5% 4 7% 10% 41%	6926
August	1st to 10th	Day	11% 6% 3 7% 5% 5% 6% 5% 8% 10% 35%	4563
	11th to 20th	Day	13% 4 1 5% 3 4 4 4 6% 8% 47%	4430
	21st to end	Day	14% 7% 2 6% 4 4 5% 4 6% 8% 40%	4378
September	1st to 10th	Day	14% 6% 3 8% 5% 5% 5% 3 5% 8% 40%	2400
	11th to 20th	Day	18% 7% 2 6% 5% 4 4 3 5% 9% 35%	2310
	21st to end	Day	17% 9% 3 7% 5% 4 5% 3 5% 7% 35%	2200
October	1st to 10th	Day	20% 12% 3 8% 4 4 4 4 5% 8% 28%	2059
	11th to 20th	Day	20% 12% 4 9% 7% 6% 4 4 5% 7% 21%	1882
	21st to end	Day	20% 14% 4 11% 6% 5% 5% 3 5% 6% 21%	1980
November	1st to 10th	Day	17% 13% 5% 9% 7% 5% 4 4 6% 7% 22%	1852
	11th to 20th	Day	20% 16% 6% 12% 6% 4 3 3 6% 5% 19%	1682
	21st to end	Day	16% 15% 6% 11% 8% 7% 6% 3 5% 4 17%	1508
December	1st to 10th	Day	10% 13% 6% 17% 8% 6% 5% 4 6% 7% 17%	2350
	11th to 20th	Day	10% 15% 5% 13% 7% 6% 5% 4 6% 7% 21%	2691
	21st to end	Day	19% 21% 7% 12% 4 3 3 3 5% 6% 16%	3619
January	1st to 10th	Night	7% 13% 5% 13% 9% 8% 7% 5% 5% 7% 22%	8233
	11th to 20th	Night	5% 13% 6% 16% 9% 7% 7% 7% 8% 6% 15%	8236
	21st to end	Night	5% 10% 6% 12% 9% 7% 8% 6% 7% 8% 22%	9058
February	1st to 10th	Night	8% 11% 5% 9% 6% 7% 7% 6% 6% 7% 27%	2913
	11th to 20th	Night	9% 11% 3 9% 7% 7% 7% 5% 7% 7% 28%	2610
	21st to end	Night	6% 13% 6% 12% 6% 6% 6% 4 5% 6% 30%	2076
March	1st to 10th	Night	12% 9% 3 9% 5% 5% 5% 4 6% 8% 33%	5482
	11th to 20th	Night	10% 14% 4 11% 6% 6% 5% 4 5% 7% 27%	5449
	21st to end	Night	15% 14% 4 9% 5% 5% 5% 4 4 5% 29%	5072
April	1st to 10th	Night	14% 12% 4 9% 6% 5% 5% 4 6% 6% 30%	2100
	11th to 20th	Night	17% 11% 4 7% 5% 3 4 4 6% 6% 33%	2019
	21st to end	Night	17% 10% 2 7% 4 4 3 4 6% 7% 35%	1844
May	1st to 10th	Night	13% 8% 2 6% 3 4 5% 4 5% 7% 42%	4688
	11th to 20th	Night	19% 9% 3 6% 4 4 4 3 5% 6% 38%	4670
	21st to end	Night	14% 5% 2 7% 3 4 4 4 6% 6% 45%	4973
June	1st to 10th	Night	15% 8% 3 7% 5% 5% 4 4 5% 7% 38%	1470
	11th to 20th	Night	15% 7% 3 9% 5% 4 4 3 6% 7% 37%	1470
	21st to end	Night	18% 7% 2 5% 4 5% 5% 4 6% 8% 35%	1470
July	1st to 10th	Night	9% 7% 3 8% 5% 4 4 4 6% 8% 42%	3428
	11th to 20th	Night	11% 7% 2 6% 4 5% 5% 4 7% 8% 41%	3620
	21st to end	Night	13% 6% 2 6% 4 4 5% 4 7% 9% 40%	3948
August	1st to 10th	Night	14% 6% 2 5% 4 5% 4 4 7% 8% 41%	2597
	11th to 20th	Night	13% 4 2 4 3 4 3 3 6% 9% 48%	2627
	21st to end	Night	17% 7% 4 6% 3 4 3 3 4 6% 43%	3516
September	1st to 10th	Night	15% 6% 3 6% 3 4 5% 3 6% 7% 43%	2000
	11th to 20th	Night	15% 8% 3 6% 4 5% 4 4 5% 7% 39%	2070
	21st to end	Night	19% 8% 3 7% 4 3 4 4 6% 7% 34%	2200
October	1st to 10th	Night	17% 10% 2 7% 5% 4 5% 4 6% 6% 34%	2339
	11th to 20th	Night	18% 10% 3 6% 5% 5% 5% 4 6% 8% 29%	2517
	21st to end	Night	20% 13% 4 9% 6% 5% 5% 3 5% 5% 25%	2860
November	1st to 10th	Night	17% 12% 4 8% 6% 5% 5% 4 6% 7% 25%	2666
	11th to 20th	Night	19% 15% 5% 13% 7% 5% 4 4 5% 5% 19%	2935
	21st to end	Night	15% 17% 5% 13% 7% 5% 5% 3 5% 6% 18%	3109
December	1st to 10th	Night	9% 17% 6% 15% 8% 6% 6% 4 6% 7% 16%	5060
	11th to 20th	Night	10% 14% 6% 13% 6% 5% 5% 4 6% 7% 24%	5736
	21st to end	Night	22% 19% 5% 13% 5% 4 4 3 5% 5% 15%	7596

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	47% 27% 10% 11% 5% 1	4692
	11th to 20th	Day	49% 26% 9% 14% 2	4710
	21st to end	Day	46% 26% 9% 11% 7%	5156
February	1st to 10th	Day	20% 61% 7% 9% 3	1706
	11th to 20th	Day	22% 59% 5% 10% 3	1906
	21st to end	Day	23% 60% 2 7% 7%	1730
March	1st to 10th	Day	37% 31% 7% 11% 12% 2	4580
	11th to 20th	Day	37% 31% 7% 14% 10%	4772
	21st to end	Day	41% 29% 4 12% 12% 2	6101
April	1st to 10th	Day	19% 60% 4 8% 8% 1	2520
	11th to 20th	Day	21% 61% 5% 10% 3 1	2550
	21st to end	Day	20% 60% 4 9% 6% 1	2772
May	1st to 10th	Day	32% 25% 8% 19% 14% 2	8250
	11th to 20th	Day	34% 25% 7% 18% 14% 2	8226
	21st to end	Day	25% 26% 10% 20% 16% 3	9234
June	1st to 10th	Day	21% 59% 4 7% 7%	3150
	11th to 20th	Day	18% 60% 6% 12% 4	3150
	21st to end	Day	20% 60% 6% 11% 4	3150
July	1st to 10th	Day	25% 30% 14% 23% 7%	6479
	11th to 20th	Day	26% 29% 17% 24% 4	6285
	21st to end	Day	26% 29% 16% 24% 6%	6728
August	1st to 10th	Day	28% 39% 10% 20% 4	4548
	11th to 20th	Day	21% 38% 15% 19% 6%	4472
	21st to end	Day	26% 40% 10% 18% 6%	4377
September	1st to 10th	Day	21% 58% 7% 10% 4	2400
	11th to 20th	Day	19% 60% 10% 10% 1	2310
	21st to end	Day	21% 58% 8% 9% 5%	2200
October	1st to 10th	Day	27% 39% 11% 13% 10%	3345
	11th to 20th	Day	31% 38% 12% 17% 2	3046
	21st to end	Day	39% 39% 12% 9% 1	3180
November	1st to 10th	Day	30% 55% 7% 6% 2	1852
	11th to 20th	Day	33% 56% 5% 4 2	1682
	21st to end	Day	34% 56% 3 4 3	1508
December	1st to 10th	Day	48% 39% 8% 3 1	2350
	11th to 20th	Day	41% 35% 11% 9% 3	2691
	21st to end	Day	52% 29% 5% 12% 1	3619
January	1st to 10th	Night	51% 25% 9% 9% 5% 2	8233
	11th to 20th	Night	53% 24% 6% 14% 3	8280
	21st to end	Night	44% 27% 9% 15% 4 1	9058
February	1st to 10th	Night	22% 61% 6% 7% 4	2913
	11th to 20th	Night	23% 60% 6% 8% 3	2611
	21st to end	Night	24% 59% 4 7% 5%	2076
March	1st to 10th	Night	34% 30% 9% 9% 13% 4	5493
	11th to 20th	Night	41% 32% 9% 13% 5% 1	5450
	21st to end	Night	42% 29% 6% 14% 9% 1	5072
April	1st to 10th	Night	21% 60% 4 9% 5%	2100
	11th to 20th	Night	19% 60% 5% 9% 6% 1	2019
	21st to end	Night	19% 60% 4 11% 5%	1844
May	1st to 10th	Night	29% 24% 10% 24% 10% 3	4695
	11th to 20th	Night	36% 24% 9% 18% 10% 2	4671
	21st to end	Night	29% 25% 8% 23% 13% 1	4974
June	1st to 10th	Night	19% 60% 3 9% 8% 1	1470
	11th to 20th	Night	19% 59% 5% 10% 7%	1470
	21st to end	Night	20% 59% 5% 11% 5%	1470
July	1st to 10th	Night	31% 29% 13% 20% 8%	3388
	11th to 20th	Night	30% 31% 17% 18% 3 1	3572
	21st to end	Night	29% 28% 11% 25% 7%	3832
August	1st to 10th	Night	24% 38% 10% 24% 4	2588
	11th to 20th	Night	21% 38% 17% 20% 5%	2651
	21st to end	Night	30% 38% 12% 13% 6%	3516
September	1st to 10th	Night	20% 59% 6% 11% 5%	2000
	11th to 20th	Night	19% 60% 10% 9% 1	2070
	21st to end	Night	20% 59% 6% 11% 4	2200
October	1st to 10th	Night	21% 39% 11% 17% 12%	3820
	11th to 20th	Night	29% 38% 9% 19% 5%	4092
	21st to end	Night	41% 38% 11% 8% 2	4610
November	1st to 10th	Night	30% 56% 7% 6% 2	2666
	11th to 20th	Night	32% 57% 6% 4 1	2935
	21st to end	Night	34% 57% 5% 3 1	3109
December	1st to 10th	Night	50% 38% 7% 4 1	5060
	11th to 20th	Night	42% 33% 11% 12% 3	5735
	21st to end	Night	56% 27% 5% 10% 2	7596

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	17% 12% 44% 22% 5%	330
	11th to 20th	Day	12% 16% 41% 23% 7% 1	330
	21st to end	Day	13% 15% 47% 17% 7% 1	363
February	1st to 10th	Day	15% 21% 41% 19% 4	330
	11th to 20th	Day	12% 21% 44% 18% 4 1	330
	21st to end	Day	19% 27% 37% 14% 3	273
March	1st to 10th	Day	18% 25% 35% 18% 4	330
	11th to 20th	Day	20% 24% 37% 14% 3 1	348
	21st to end	Day	20% 18% 36% 18% 6% 2	594
April	1st to 10th	Day	20% 21% 30% 22% 7% 1	540
	11th to 20th	Day	26% 20% 26% 17% 9% 1	532
	21st to end	Day	24% 18% 30% 18% 8% 3	582
May	1st to 10th	Day	18% 19% 36% 19% 6% 2	753
	11th to 20th	Day	20% 19% 35% 18% 6% 2	775
	21st to end	Day	20% 18% 35% 20% 5% 2	844
June	1st to 10th	Day	19% 14% 41% 19% 6% 2	780
	11th to 20th	Day	16% 19% 37% 20% 6% 1	780
	21st to end	Day	19% 14% 37% 21% 8% 2	780
July	1st to 10th	Day	11% 10% 39% 28% 9% 2	722
	11th to 20th	Day	12% 14% 42% 22% 9% 2	718
	21st to end	Day	12% 12% 35% 25% 11% 4	794
August	1st to 10th	Day	12% 14% 36% 26% 9% 3	726
	11th to 20th	Day	15% 12% 30% 28% 12% 4	675
	21st to end	Day	19% 13% 31% 24% 11% 2	583
September	1st to 10th	Day	16% 14% 30% 26% 12% 3	530
	11th to 20th	Day	21% 14% 29% 22% 13% 1	530
	21st to end	Day	20% 16% 28% 22% 12% 3	530
October	1st to 10th	Day	24% 23% 29% 16% 6% 2	389
	11th to 20th	Day	23% 23% 35% 16% 3	330
	21st to end	Day	27% 26% 33% 10% 4	363
November	1st to 10th	Day	22% 25% 33% 16% 4	330
	11th to 20th	Day	31% 23% 32% 10% 4	330
	21st to end	Day	23% 26% 32% 15% 4	239
December	1st to 10th	Day	18% 15% 35% 23% 7% 2	220
	11th to 20th	Day	21% 22% 31% 18% 6% 1	220
	21st to end	Day	23% 19% 30% 21% 6% 1	257
January	1st to 10th	Night	17% 13% 39% 26% 5% 1	1050
	11th to 20th	Night	16% 14% 34% 26% 8% 2	1050
	21st to end	Night	15% 9% 35% 30% 10% 1	1155
February	1st to 10th	Night	15% 11% 35% 29% 9% 1	1050
	11th to 20th	Night	15% 12% 35% 26% 11% 1	976
	21st to end	Night	15% 11% 38% 27% 9% 1	692
March	1st to 10th	Night	14% 12% 37% 27% 10% 1	840
	11th to 20th	Night	18% 15% 35% 27% 5% 1	814
	21st to end	Night	16% 11% 30% 29% 12% 2	693
April	1st to 10th	Night	19% 10% 31% 32% 7% 1	630
	11th to 20th	Night	22% 10% 28% 28% 10% 1	623
	21st to end	Night	23% 7% 28% 30% 12% 1	630
May	1st to 10th	Night	21% 8% 27% 32% 10% 1	630
	11th to 20th	Night	20% 9% 28% 33% 8% 1	621
	21st to end	Night	22% 8% 25% 34% 10% 1	625
June	1st to 10th	Night	14% 10% 35% 30% 11% 1	420
	11th to 20th	Night	17% 9% 29% 36% 8%	420
	21st to end	Night	19% 7% 30% 35% 8% 1	420
July	1st to 10th	Night	13% 5% 30% 38% 13% 1	497
	11th to 20th	Night	12% 6% 27% 40% 12% 1	582
	21st to end	Night	10% 5% 25% 42% 18% 2	657
August	1st to 10th	Night	14% 4 24% 43% 15%	597
	11th to 20th	Night	15% 4 22% 35% 23% 2	594
	21st to end	Night	17% 7% 30% 31% 15% 1	660
September	1st to 10th	Night	17% 8% 23% 34% 16% 3	600
	11th to 20th	Night	20% 10% 29% 28% 12% 2	670
	21st to end	Night	22% 10% 27% 28% 13% 1	800
October	1st to 10th	Night	22% 14% 30% 24% 9% 1	800
	11th to 20th	Night	25% 13% 31% 22% 8% 1	800
	21st to end	Night	28% 11% 31% 23% 7%	880
November	1st to 10th	Night	24% 16% 31% 22% 6%	820
	11th to 20th	Night	29% 14% 29% 21% 6% 1	1045
	21st to end	Night	24% 18% 29% 23% 5%	1050
December	1st to 10th	Night	18% 15% 36% 23% 7% 1	1050
	11th to 20th	Night	18% 14% 32% 26% 8% 1	1050
	21st to end	Night	25% 13% 28% 26% 7% 1	1155

Page generated at 2026-06-28 02:10:46. Version ac07

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