Rouyn-Noranda
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rouyn-Noranda clear sky chart from 2005-11-06 to 2025-10-19.

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	16% 12% 4 10% 6% 5% 5% 4 5% 6% 27%	127091
	Night	16% 14% 5% 11% 6% 5% 5% 3 5% 5% 25%	122720
Transparency	Day	57% 5% 11% 18% 8% 1	130570
	Night	61% 5% 10% 16% 7% 1	127330
Seeing	Day	23% 14% 32% 21% 8% 2	16426
	Night	24% 12% 30% 25% 8% 1	25278

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	11% 21% 9% 21% 9% 7% 5% 3 4 3 8%	3158
	11th to 20th	Day	9% 18% 7% 18% 9% 5% 5% 4 7% 5% 12%	3133
	21st to end	Day	9% 17% 8% 15% 6% 7% 6% 4 5% 5% 17%	4191
February	1st to 10th	Day	8% 16% 6% 12% 8% 9% 7% 6% 6% 7% 16%	1800
	11th to 20th	Day	10% 18% 7% 12% 7% 6% 6% 4 5% 5% 19%	1753
	21st to end	Day	12% 17% 5% 12% 6% 5% 5% 4 5% 5% 22%	1485
March	1st to 10th	Day	18% 16% 4 10% 7% 4 5% 3 5% 5% 23%	4803
	11th to 20th	Day	17% 15% 5% 14% 6% 5% 4 2 3 4 25%	4980
	21st to end	Day	13% 15% 5% 13% 6% 6% 5% 3 4 4 26%	5504
April	1st to 10th	Day	18% 16% 4 9% 5% 5% 5% 4 5% 6% 25%	2400
	11th to 20th	Day	20% 11% 4 9% 5% 3 3 3 4 6% 31%	2526
	21st to end	Day	19% 13% 4 8% 4 4 4 3 4 5% 31%	2600
May	1st to 10th	Day	17% 10% 3 8% 5% 4 4 3 5% 6% 35%	6298
	11th to 20th	Day	13% 8% 3 7% 6% 5% 5% 4 6% 6% 36%	6318
	21st to end	Day	18% 11% 3 7% 4 4 3 3 5% 6% 36%	7082
June	1st to 10th	Day	21% 8% 3 7% 5% 5% 5% 4 5% 7% 30%	3000
	11th to 20th	Day	15% 7% 3 8% 5% 5% 5% 4 6% 7% 35%	3000
	21st to end	Day	19% 9% 3 7% 5% 5% 5% 4 6% 7% 31%	3000
July	1st to 10th	Day	14% 7% 3 7% 6% 6% 5% 4 7% 10% 30%	6819
	11th to 20th	Day	15% 6% 2 6% 5% 5% 5% 4 7% 10% 35%	6820
	21st to end	Day	15% 7% 3 7% 5% 4 4 4 6% 9% 35%	7070
August	1st to 10th	Day	14% 7% 3 7% 5% 5% 6% 5% 7% 9% 32%	4351
	11th to 20th	Day	17% 8% 3 6% 4 4 5% 5% 6% 7% 36%	4174
	21st to end	Day	14% 7% 3 7% 4 4 4 4 6% 8% 38%	4581
September	1st to 10th	Day	20% 7% 3 8% 4 5% 4 5% 6% 8% 31%	2400
	11th to 20th	Day	20% 8% 3 6% 4 4 4 4 6% 7% 34%	2339
	21st to end	Day	23% 11% 3 6% 4 3 4 3 4 6% 32%	2127
October	1st to 10th	Day	22% 11% 3 8% 4 4 4 4 4 6% 31%	2000
	11th to 20th	Day	27% 19% 4 7% 4 3 5% 3 5% 4 19%	1980
	21st to end	Day	26% 19% 5% 10% 5% 5% 5% 3 3 4 15%	1963
November	1st to 10th	Day	21% 20% 6% 10% 6% 4 4 3 5% 5% 17%	1566
	11th to 20th	Day	20% 18% 7% 16% 6% 5% 4 3 3 4 13%	1600
	21st to end	Day	25% 23% 8% 14% 7% 4 3 2 3 3 8%	1600
December	1st to 10th	Day	13% 24% 11% 18% 10% 4 4 2 3 3 7%	2573
	11th to 20th	Day	12% 20% 7% 16% 9% 8% 4 3 3 4 16%	2621
	21st to end	Day	18% 22% 7% 16% 7% 6% 4 3 4 4 8%	3476
January	1st to 10th	Night	9% 20% 10% 21% 9% 7% 4 3 3 3 11%	6808
	11th to 20th	Night	10% 16% 8% 18% 8% 6% 6% 5% 6% 4 14%	6772
	21st to end	Night	8% 17% 9% 15% 7% 7% 8% 4 5% 4 16%	6761
February	1st to 10th	Night	10% 17% 5% 10% 10% 6% 7% 4 5% 6% 19%	2600
	11th to 20th	Night	11% 16% 7% 13% 8% 6% 5% 3 3 5% 22%	2533
	21st to end	Night	9% 17% 6% 13% 7% 8% 6% 3 5% 6% 20%	2145
March	1st to 10th	Night	17% 17% 5% 10% 6% 4 3 4 4 4 25%	5035
	11th to 20th	Night	17% 19% 6% 13% 7% 5% 5% 3 4 4 18%	4979
	21st to end	Night	13% 14% 6% 11% 7% 6% 4 3 4 5% 26%	5427
April	1st to 10th	Night	18% 16% 5% 9% 5% 4 4 3 4 4 28%	2000
	11th to 20th	Night	19% 9% 3 7% 6% 5% 4 4 5% 7% 32%	1841
	21st to end	Night	20% 11% 4 9% 4 4 3 3 5% 6% 33%	1800
May	1st to 10th	Night	18% 9% 4 7% 5% 5% 4 3 4 6% 35%	3640
	11th to 20th	Night	15% 8% 2 6% 3 3 4 4 5% 7% 43%	3575
	21st to end	Night	20% 8% 2 6% 4 4 5% 4 6% 6% 35%	3795
June	1st to 10th	Night	17% 11% 3 8% 5% 4 4 4 5% 8% 31%	1400
	11th to 20th	Night	14% 7% 3 6% 5% 4 4 3 5% 7% 41%	1400
	21st to end	Night	17% 7% 3 7% 5% 5% 5% 4 5% 7% 37%	1400
July	1st to 10th	Night	17% 8% 3 7% 4 4 4 4 5% 6% 36%	3160
	11th to 20th	Night	17% 7% 3 7% 5% 4 4 4 6% 7% 36%	3160
	21st to end	Night	12% 6% 2 6% 4 4 4 4 6% 9% 43%	3786
August	1st to 10th	Night	9% 6% 3 7% 6% 5% 5% 4 6% 8% 41%	2783
	11th to 20th	Night	14% 8% 3 7% 5% 4 4 4 5% 7% 39%	2875
	21st to end	Night	16% 7% 3 7% 4 4 3 3 5% 7% 41%	3284
September	1st to 10th	Night	18% 8% 3 7% 4 4 5% 4 5% 6% 36%	2000
	11th to 20th	Night	18% 8% 3 5% 4 3 4 3 5% 7% 40%	2059
	21st to end	Night	21% 8% 2 6% 4 3 4 3 4 6% 38%	2272
October	1st to 10th	Night	20% 11% 4 7% 5% 4 4 3 4 6% 32%	2400
	11th to 20th	Night	25% 17% 5% 9% 5% 4 4 3 4 5% 19%	2377
	21st to end	Night	23% 21% 5% 9% 4 4 4 3 4 5% 18%	2630
November	1st to 10th	Night	20% 17% 5% 10% 5% 5% 4 3 5% 5% 20%	2732
	11th to 20th	Night	20% 17% 6% 13% 7% 5% 4 4 4 4 16%	2800
	21st to end	Night	23% 22% 7% 13% 7% 5% 4 3 4 4 9%	2800
December	1st to 10th	Night	14% 23% 9% 16% 11% 7% 5% 3 3 3 7%	4603
	11th to 20th	Night	16% 19% 7% 13% 9% 8% 6% 4 4 4 12%	5586
	21st to end	Night	20% 21% 8% 14% 7% 3 3 2 4 4 14%	7502

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	83% 2 7% 6% 2	3159
	11th to 20th	Day	72% 4 7% 11% 6%	3160
	21st to end	Day	69% 3 7% 15% 6%	4191
February	1st to 10th	Day	66% 6% 8% 13% 7%	1800
	11th to 20th	Day	67% 4 9% 13% 7%	1762
	21st to end	Day	64% 3 8% 17% 7% 1	1485
March	1st to 10th	Day	64% 4 6% 14% 11% 1	4806
	11th to 20th	Day	65% 3 9% 15% 7% 1	4980
	21st to end	Day	62% 4 7% 18% 7% 1	5504
April	1st to 10th	Day	61% 5% 10% 15% 9% 1	2400
	11th to 20th	Day	56% 4 9% 20% 11% 1	2526
	21st to end	Day	55% 5% 8% 16% 13% 2	2600
May	1st to 10th	Day	48% 6% 8% 17% 17% 3	6309
	11th to 20th	Day	47% 6% 14% 21% 9% 3	6322
	21st to end	Day	50% 5% 9% 18% 15% 3	7082
June	1st to 10th	Day	52% 6% 11% 20% 10% 1	3000
	11th to 20th	Day	46% 6% 11% 23% 13% 1	3000
	21st to end	Day	51% 6% 12% 20% 10% 1	3000
July	1st to 10th	Day	46% 7% 16% 25% 6%	6746
	11th to 20th	Day	43% 6% 19% 25% 7%	6739
	21st to end	Day	45% 5% 14% 28% 7%	6869
August	1st to 10th	Day	46% 8% 17% 24% 5%	4337
	11th to 20th	Day	46% 6% 15% 23% 8% 1	4213
	21st to end	Day	43% 6% 14% 28% 9% 1	4581
September	1st to 10th	Day	50% 8% 14% 21% 7% 1	2400
	11th to 20th	Day	48% 7% 17% 23% 4	2339
	21st to end	Day	54% 4 13% 22% 7%	2127
October	1st to 10th	Day	59% 4 11% 19% 5% 1	3260
	11th to 20th	Day	61% 5% 11% 16% 6%	3220
	21st to end	Day	69% 5% 14% 6% 5%	3217
November	1st to 10th	Day	70% 4 13% 8% 4	1566
	11th to 20th	Day	76% 4 9% 9% 2	1600
	21st to end	Day	84% 3 7% 4 2	1600
December	1st to 10th	Day	83% 3 7% 5% 1	2573
	11th to 20th	Day	74% 4 7% 14% 2	2621
	21st to end	Day	80% 3 5% 8% 2	3476
January	1st to 10th	Night	80% 3 9% 5% 2	6808
	11th to 20th	Night	73% 4 7% 9% 7%	6820
	21st to end	Night	71% 3 5% 14% 6%	6761
February	1st to 10th	Night	65% 4 9% 14% 9%	2600
	11th to 20th	Night	66% 4 8% 14% 7%	2535
	21st to end	Night	66% 4 8% 14% 8% 1	2145
March	1st to 10th	Night	64% 3 8% 11% 10% 4	5045
	11th to 20th	Night	71% 5% 8% 10% 6% 1	4980
	21st to end	Night	60% 4 7% 16% 10% 3	5427
April	1st to 10th	Night	59% 4 7% 16% 12% 1	2000
	11th to 20th	Night	51% 4 9% 20% 14% 1	1841
	21st to end	Night	53% 5% 7% 16% 17% 2	1800
May	1st to 10th	Night	49% 6% 9% 17% 17% 1	3646
	11th to 20th	Night	40% 6% 15% 23% 13% 3	3576
	21st to end	Night	47% 6% 11% 18% 15% 3	3796
June	1st to 10th	Night	52% 6% 9% 20% 11% 1	1400
	11th to 20th	Night	42% 6% 10% 23% 16% 3	1400
	21st to end	Night	45% 6% 14% 21% 13% 1	1400
July	1st to 10th	Night	48% 6% 11% 26% 10%	3125
	11th to 20th	Night	46% 6% 14% 26% 8%	3118
	21st to end	Night	38% 6% 18% 32% 6%	3673
August	1st to 10th	Night	40% 6% 17% 31% 6%	2773
	11th to 20th	Night	44% 6% 15% 30% 5%	2902
	21st to end	Night	43% 5% 15% 25% 9% 2	3284
September	1st to 10th	Night	47% 6% 16% 21% 8% 1	2000
	11th to 20th	Night	44% 7% 18% 25% 6%	2059
	21st to end	Night	46% 6% 15% 25% 7%	2272
October	1st to 10th	Night	53% 5% 12% 21% 8%	3920
	11th to 20th	Night	62% 4 11% 20% 3	3876
	21st to end	Night	63% 5% 15% 10% 5%	4326
November	1st to 10th	Night	67% 5% 13% 13% 2	2732
	11th to 20th	Night	72% 4 11% 9% 3	2800
	21st to end	Night	81% 5% 7% 7% 1	2800
December	1st to 10th	Night	84% 4 5% 5% 1	4603
	11th to 20th	Night	77% 3 7% 9% 3	5585
	21st to end	Night	77% 2 6% 11% 4	7502

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	24% 21% 38% 14% 4 1	200
	11th to 20th	Day	16% 17% 37% 23% 6% 3	200
	21st to end	Day	19% 12% 36% 24% 8% 1	286
February	1st to 10th	Day	15% 26% 39% 16% 3 1	300
	11th to 20th	Day	19% 20% 39% 17% 5%	300
	21st to end	Day	23% 24% 37% 14% 1	249
March	1st to 10th	Day	21% 14% 42% 16% 7%	485
	11th to 20th	Day	23% 18% 34% 20% 6%	500
	21st to end	Day	25% 18% 34% 17% 5% 1	550
April	1st to 10th	Day	22% 22% 27% 18% 8% 2	500
	11th to 20th	Day	26% 17% 27% 20% 7% 2	492
	21st to end	Day	28% 20% 25% 17% 8% 2	500
May	1st to 10th	Day	21% 15% 34% 20% 9% 2	503
	11th to 20th	Day	23% 14% 31% 20% 7% 4	527
	21st to end	Day	23% 14% 30% 23% 8% 1	628
June	1st to 10th	Day	23% 12% 36% 21% 7% 1	730
	11th to 20th	Day	19% 17% 30% 23% 8% 2	730
	21st to end	Day	21% 12% 29% 25% 10% 2	730
July	1st to 10th	Day	16% 12% 34% 26% 10% 2	721
	11th to 20th	Day	16% 11% 32% 26% 14% 1	718
	21st to end	Day	15% 9% 34% 27% 11% 4	642
August	1st to 10th	Day	16% 10% 29% 27% 12% 6%	526
	11th to 20th	Day	17% 9% 25% 27% 16% 7%	519
	21st to end	Day	21% 11% 29% 19% 14% 6%	583
September	1st to 10th	Day	22% 11% 32% 22% 11% 3	530
	11th to 20th	Day	21% 8% 29% 25% 12% 5%	530
	21st to end	Day	27% 10% 27% 21% 13% 2	530
October	1st to 10th	Day	26% 14% 31% 18% 9% 2	530
	11th to 20th	Day	34% 18% 28% 16% 3 1	522
	21st to end	Day	36% 14% 31% 15% 3 1	445
November	1st to 10th	Day	34% 20% 36% 9% 2	200
	11th to 20th	Day	24% 24% 29% 21% 3 1	200
	21st to end	Day	41% 17% 30% 9% 2 2	200
December	1st to 10th	Day	27% 15% 32% 18% 9% 1	200
	11th to 20th	Day	24% 15% 40% 16% 6% 1	200
	21st to end	Day	33% 12% 34% 15% 6% 1	220
January	1st to 10th	Night	23% 14% 35% 22% 5% 1	1000
	11th to 20th	Night	25% 11% 34% 23% 7%	1000
	21st to end	Night	18% 10% 29% 30% 11% 1	910
February	1st to 10th	Night	18% 13% 36% 26% 6%	800
	11th to 20th	Night	21% 13% 35% 26% 5%	783
	21st to end	Night	18% 17% 37% 22% 6%	660
March	1st to 10th	Night	20% 17% 33% 23% 7% 1	800
	11th to 20th	Night	26% 16% 31% 23% 5% 1	800
	21st to end	Night	20% 12% 36% 25% 6% 1	880
April	1st to 10th	Night	26% 14% 31% 22% 7% 1	800
	11th to 20th	Night	24% 15% 27% 25% 8% 1	657
	21st to end	Night	24% 10% 31% 28% 6% 1	600
May	1st to 10th	Night	20% 9% 33% 28% 10%	420
	11th to 20th	Night	22% 10% 29% 30% 7% 2	394
	21st to end	Night	23% 8% 29% 33% 6%	433
June	1st to 10th	Night	22% 9% 34% 27% 9%	400
	11th to 20th	Night	19% 11% 30% 31% 10%	400
	21st to end	Night	18% 7% 28% 33% 14%	400
July	1st to 10th	Night	17% 7% 26% 38% 12% 1	390
	11th to 20th	Night	18% 4 29% 38% 11% 1	388
	21st to end	Night	13% 7% 27% 37% 16% 1	438
August	1st to 10th	Night	17% 4 27% 31% 21% 1	517
	11th to 20th	Night	17% 6% 24% 31% 20% 3	594
	21st to end	Night	23% 7% 24% 29% 16% 1	695
September	1st to 10th	Night	21% 11% 28% 27% 13% 1	800
	11th to 20th	Night	21% 9% 26% 28% 16% 1	800
	21st to end	Night	24% 9% 23% 31% 13% 1	800
October	1st to 10th	Night	26% 12% 26% 26% 9% 1	800
	11th to 20th	Night	35% 13% 28% 18% 6% 1	793
	21st to end	Night	33% 12% 31% 19% 4 1	836
November	1st to 10th	Night	30% 12% 34% 18% 5% 1	780
	11th to 20th	Night	30% 15% 32% 18% 5% 1	800
	21st to end	Night	35% 13% 34% 14% 4 1	800
December	1st to 10th	Night	30% 13% 29% 20% 7% 1	810
	11th to 20th	Night	28% 13% 31% 21% 6% 1	1000
	21st to end	Night	29% 13% 27% 22% 7% 2	1100

Page generated at 2025-10-16 01:50:23. Version ac07

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