Club d'Astronomie Sirius du Saguenay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Club d'Astronomie Sirius du Saguenay clear sky chart from 2005-11-06 to 2024-11-11.

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	17% 11% 4 10% 6% 5% 5% 4 6% 7% 25%	101739
	Night	17% 14% 4 10% 6% 5% 5% 4 5% 6% 23%	97486
Transparency	Day	56% 9% 13% 15% 5%	105179
	Night	60% 8% 11% 14% 5%	102135
Seeing	Day	25% 16% 29% 20% 8% 1	15443
	Night	25% 14% 27% 25% 8% 1	23676

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% 19% 10% 19% 8% 5% 5% 3 5% 4 11%	2363
	11th to 20th	Day	12% 12% 6% 19% 12% 8% 9% 4 5% 4 9%	2520
	21st to end	Day	8% 14% 7% 14% 6% 8% 6% 5% 6% 5% 21%	2772
February	1st to 10th	Day	6% 14% 5% 12% 8% 10% 8% 5% 7% 6% 18%	1520
	11th to 20th	Day	11% 16% 5% 15% 9% 8% 6% 3 6% 4 16%	1746
	21st to end	Day	9% 16% 5% 10% 8% 8% 7% 6% 6% 6% 21%	1570
March	1st to 10th	Day	14% 13% 3 9% 5% 4 4 4 6% 6% 31%	3116
	11th to 20th	Day	15% 18% 6% 13% 7% 5% 5% 4 4 5% 18%	3318
	21st to end	Day	12% 13% 5% 12% 5% 5% 6% 4 5% 7% 26%	4058
April	1st to 10th	Day	17% 15% 5% 10% 5% 5% 4 3 4 5% 24%	2280
	11th to 20th	Day	18% 10% 4 8% 6% 5% 5% 3 5% 7% 30%	2378
	21st to end	Day	18% 10% 4 7% 5% 5% 4 4 5% 6% 30%	2470
May	1st to 10th	Day	18% 11% 3 7% 5% 5% 4 4 5% 6% 32%	4316
	11th to 20th	Day	17% 7% 3 7% 5% 5% 5% 4 6% 8% 33%	4398
	21st to end	Day	18% 8% 3 8% 5% 5% 5% 4 6% 8% 31%	5150
June	1st to 10th	Day	20% 9% 3 7% 6% 5% 4 4 6% 6% 30%	2850
	11th to 20th	Day	18% 6% 2 7% 5% 5% 5% 5% 6% 7% 32%	2850
	21st to end	Day	23% 8% 3 7% 5% 6% 5% 4 5% 7% 28%	2850
July	1st to 10th	Day	18% 9% 3 8% 5% 4 5% 5% 7% 8% 27%	4760
	11th to 20th	Day	17% 8% 3 9% 6% 5% 6% 4 6% 8% 27%	4484
	21st to end	Day	15% 8% 2 8% 6% 5% 5% 4 6% 9% 33%	4814
August	1st to 10th	Day	16% 8% 3 8% 5% 6% 6% 5% 8% 9% 26%	4423
	11th to 20th	Day	19% 7% 3 9% 5% 6% 5% 5% 8% 9% 25%	4088
	21st to end	Day	18% 8% 3 9% 5% 5% 4 3 5% 7% 32%	4414
September	1st to 10th	Day	21% 8% 3 7% 5% 5% 5% 5% 5% 7% 29%	2280
	11th to 20th	Day	20% 8% 3 6% 4 4 4 3 5% 8% 34%	2118
	21st to end	Day	24% 9% 3 6% 4 4 4 3 5% 7% 31%	2090
October	1st to 10th	Day	20% 10% 3 8% 6% 4 4 3 5% 7% 29%	2071
	11th to 20th	Day	27% 14% 5% 9% 6% 5% 5% 4 4 5% 15%	1715
	21st to end	Day	28% 17% 4 9% 5% 4 4 2 4 4 21%	1881
November	1st to 10th	Day	22% 17% 5% 12% 6% 4 4 3 4 5% 19%	1761
	11th to 20th	Day	21% 20% 5% 11% 7% 5% 4 3 5% 4 14%	1556
	21st to end	Day	20% 22% 6% 12% 6% 5% 5% 3 4 4 11%	1330
December	1st to 10th	Day	19% 21% 6% 15% 9% 6% 5% 2 3 3 10%	1330
	11th to 20th	Day	18% 17% 6% 13% 7% 7% 6% 3 4 3 15%	1668
	21st to end	Day	17% 19% 5% 12% 9% 6% 4 4 4 5% 13%	2431
January	1st to 10th	Night	11% 21% 7% 13% 10% 8% 6% 4 4 4 11%	4584
	11th to 20th	Night	12% 17% 5% 19% 11% 6% 6% 4 4 4 12%	4440
	21st to end	Night	7% 17% 7% 13% 8% 7% 5% 4 6% 6% 20%	4884
February	1st to 10th	Night	8% 15% 5% 12% 8% 6% 6% 5% 6% 7% 21%	2660
	11th to 20th	Night	10% 19% 6% 15% 9% 7% 4 3 5% 4 17%	2318
	21st to end	Night	9% 18% 6% 12% 8% 4 6% 3 6% 5% 23%	1884
March	1st to 10th	Night	20% 14% 4 9% 6% 5% 6% 5% 4 5% 22%	3724
	11th to 20th	Night	14% 19% 5% 13% 8% 6% 6% 4 4 6% 17%	3640
	21st to end	Night	12% 16% 5% 12% 6% 5% 4 3 6% 6% 27%	3572
April	1st to 10th	Night	21% 15% 4 10% 6% 4 4 3 4 5% 26%	1900
	11th to 20th	Night	21% 12% 3 7% 4 5% 4 3 4 6% 30%	1750
	21st to end	Night	19% 11% 3 5% 5% 4 4 3 6% 6% 33%	1710
May	1st to 10th	Night	21% 9% 3 8% 5% 4 4 3 5% 6% 33%	2655
	11th to 20th	Night	20% 10% 3 8% 5% 4 4 3 4 6% 34%	2495
	21st to end	Night	20% 9% 3 8% 5% 4 5% 4 5% 7% 30%	2435
June	1st to 10th	Night	20% 7% 3 7% 5% 4 5% 4 6% 7% 30%	1330
	11th to 20th	Night	17% 9% 4 6% 5% 5% 5% 3 5% 8% 34%	1330
	21st to end	Night	21% 9% 3 7% 5% 5% 4 4 5% 7% 29%	1330
July	1st to 10th	Night	19% 8% 3 9% 5% 5% 5% 4 5% 8% 28%	2210
	11th to 20th	Night	16% 8% 3 8% 6% 6% 6% 5% 6% 7% 27%	2474
	21st to end	Night	13% 7% 3 7% 4 5% 5% 4 7% 8% 38%	2739
August	1st to 10th	Night	17% 8% 3 8% 6% 5% 6% 5% 7% 8% 27%	2506
	11th to 20th	Night	19% 7% 3 7% 6% 6% 6% 4 6% 8% 26%	2709
	21st to end	Night	16% 7% 3 9% 5% 5% 5% 4 7% 7% 32%	3239
September	1st to 10th	Night	21% 7% 3 6% 5% 4 4 4 5% 7% 34%	1900
	11th to 20th	Night	19% 7% 3 8% 5% 5% 5% 4 5% 5% 33%	2061
	21st to end	Night	21% 8% 3 7% 5% 5% 5% 2 4 7% 32%	2090
October	1st to 10th	Night	22% 8% 2 7% 6% 4 4 3 5% 7% 32%	2107
	11th to 20th	Night	30% 12% 3 8% 4 5% 5% 3 4 6% 20%	2465
	21st to end	Night	27% 15% 4 8% 4 5% 4 3 5% 6% 19%	2717
November	1st to 10th	Night	25% 18% 4 10% 5% 4 4 3 4 4 19%	2537
	11th to 20th	Night	20% 18% 5% 10% 6% 5% 5% 4 4 6% 18%	2624
	21st to end	Night	20% 22% 6% 13% 6% 5% 4 3 4 3 13%	2850
December	1st to 10th	Night	19% 22% 7% 14% 7% 6% 5% 4 4 3 10%	2850
	11th to 20th	Night	19% 18% 6% 13% 8% 5% 4 4 5% 5% 13%	3531
	21st to end	Night	16% 25% 7% 12% 6% 4 4 3 3 3 17%	5236

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	73% 9% 8% 8% 1	2364
	11th to 20th	Day	78% 7% 6% 6% 3	2520
	21st to end	Day	61% 9% 7% 15% 7%	2772
February	1st to 10th	Day	63% 9% 10% 12% 6% 1	1520
	11th to 20th	Day	69% 7% 10% 9% 5%	1754
	21st to end	Day	61% 10% 10% 14% 5% 1	1570
March	1st to 10th	Day	48% 12% 17% 15% 6% 1	3119
	11th to 20th	Day	66% 8% 11% 11% 5%	3318
	21st to end	Day	55% 9% 11% 16% 8% 2	4058
April	1st to 10th	Day	62% 8% 10% 11% 6% 2	2280
	11th to 20th	Day	52% 9% 11% 18% 8% 1	2378
	21st to end	Day	53% 9% 11% 16% 11% 1	2470
May	1st to 10th	Day	48% 10% 15% 17% 10% 1	4330
	11th to 20th	Day	45% 11% 14% 21% 7% 1	4402
	21st to end	Day	48% 10% 12% 19% 10% 1	5150
June	1st to 10th	Day	52% 9% 11% 16% 11% 1	2850
	11th to 20th	Day	49% 9% 13% 19% 10% 1	2850
	21st to end	Day	54% 9% 12% 16% 7% 1	2850
July	1st to 10th	Day	51% 9% 15% 23% 3	4685
	11th to 20th	Day	52% 9% 18% 17% 3	4407
	21st to end	Day	47% 11% 18% 19% 5%	4661
August	1st to 10th	Day	49% 12% 17% 19% 2	4409
	11th to 20th	Day	52% 11% 21% 13% 3	4128
	21st to end	Day	51% 8% 16% 17% 8%	4414
September	1st to 10th	Day	52% 10% 14% 19% 6%	2280
	11th to 20th	Day	48% 11% 16% 20% 6%	2118
	21st to end	Day	53% 10% 14% 18% 5%	2090
October	1st to 10th	Day	55% 10% 11% 20% 4 1	3448
	11th to 20th	Day	67% 9% 13% 10% 1	2827
	21st to end	Day	62% 9% 15% 12% 2	3081
November	1st to 10th	Day	67% 10% 12% 9% 2	1761
	11th to 20th	Day	73% 8% 9% 8% 2	1556
	21st to end	Day	76% 10% 9% 5% 1	1330
December	1st to 10th	Day	80% 6% 7% 6% 1	1330
	11th to 20th	Day	71% 8% 7% 10% 3	1668
	21st to end	Day	70% 9% 8% 8% 5% 1	2431
January	1st to 10th	Night	75% 9% 8% 6% 2	4584
	11th to 20th	Night	72% 9% 8% 8% 3	4440
	21st to end	Night	62% 8% 10% 14% 6%	4884
February	1st to 10th	Night	60% 8% 10% 15% 6%	2660
	11th to 20th	Night	69% 5% 10% 11% 5%	2320
	21st to end	Night	61% 8% 10% 16% 6%	1884
March	1st to 10th	Night	61% 9% 10% 14% 5% 1	3734
	11th to 20th	Night	65% 10% 10% 10% 4 1	3641
	21st to end	Night	56% 8% 8% 19% 8% 1	3572
April	1st to 10th	Night	62% 5% 9% 14% 8% 2	1900
	11th to 20th	Night	54% 7% 10% 17% 12% 1	1750
	21st to end	Night	50% 7% 11% 20% 10% 2	1710
May	1st to 10th	Night	50% 9% 12% 17% 12% 1	2661
	11th to 20th	Night	46% 9% 11% 22% 11% 1	2496
	21st to end	Night	49% 10% 11% 18% 12%	2436
June	1st to 10th	Night	50% 9% 13% 18% 8% 2	1330
	11th to 20th	Night	47% 8% 13% 18% 12% 3	1330
	21st to end	Night	53% 10% 11% 18% 9%	1330
July	1st to 10th	Night	53% 7% 12% 23% 5%	2175
	11th to 20th	Night	50% 11% 18% 18% 3	2428
	21st to end	Night	43% 11% 20% 19% 8%	2651
August	1st to 10th	Night	50% 11% 18% 17% 4	2496
	11th to 20th	Night	52% 12% 19% 13% 3	2735
	21st to end	Night	49% 9% 13% 24% 5%	3239
September	1st to 10th	Night	48% 10% 15% 20% 8%	1900
	11th to 20th	Night	52% 9% 16% 17% 6%	2061
	21st to end	Night	51% 9% 12% 21% 7%	2090
October	1st to 10th	Night	55% 9% 12% 19% 5% 1	3510
	11th to 20th	Night	63% 8% 10% 16% 3	4092
	21st to end	Night	64% 7% 14% 11% 3	4467
November	1st to 10th	Night	67% 8% 11% 10% 3	2537
	11th to 20th	Night	70% 8% 10% 9% 3	2624
	21st to end	Night	75% 7% 10% 6% 1	2850
December	1st to 10th	Night	77% 8% 8% 6% 2	2850
	11th to 20th	Night	72% 7% 8% 10% 2	3532
	21st to end	Night	71% 6% 8% 10% 3	5236

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	21% 20% 41% 13% 6%	180
	11th to 20th	Day	23% 16% 37% 18% 6% 1	180
	21st to end	Day	15% 18% 35% 23% 7% 2	198
February	1st to 10th	Day	19% 25% 39% 12% 3 2	180
	11th to 20th	Day	21% 25% 33% 18% 4	385
	21st to end	Day	24% 22% 30% 18% 6%	382
March	1st to 10th	Day	25% 15% 35% 18% 7%	460
	11th to 20th	Day	26% 20% 27% 18% 8% 1	460
	21st to end	Day	28% 21% 26% 18% 7%	506
April	1st to 10th	Day	28% 19% 28% 19% 5% 1	460
	11th to 20th	Day	27% 14% 34% 18% 5% 1	452
	21st to end	Day	25% 22% 31% 16% 5% 1	460
May	1st to 10th	Day	30% 17% 27% 19% 6% 1	463
	11th to 20th	Day	17% 17% 32% 24% 8% 1	487
	21st to end	Day	27% 17% 30% 20% 6%	712
June	1st to 10th	Day	25% 13% 32% 23% 7%	680
	11th to 20th	Day	21% 14% 29% 24% 11% 2	680
	21st to end	Day	25% 11% 30% 23% 9% 1	680
July	1st to 10th	Day	23% 11% 29% 27% 10% 1	670
	11th to 20th	Day	21% 12% 29% 26% 11% 2	513
	21st to end	Day	20% 13% 30% 23% 13% 2	532
August	1st to 10th	Day	23% 11% 26% 27% 10% 4	486
	11th to 20th	Day	19% 11% 23% 29% 16% 3	479
	21st to end	Day	24% 14% 25% 17% 15% 5%	539
September	1st to 10th	Day	26% 14% 27% 19% 10% 4	490
	11th to 20th	Day	23% 13% 25% 25% 11% 4	490
	21st to end	Day	28% 13% 24% 23% 10% 2	490
October	1st to 10th	Day	24% 16% 27% 18% 11% 4	490
	11th to 20th	Day	38% 16% 22% 13% 9% 2	393
	21st to end	Day	37% 18% 24% 15% 5%	429
November	1st to 10th	Day	37% 18% 25% 16% 4	395
	11th to 20th	Day	30% 19% 27% 16% 6% 1	304
	21st to end	Day	32% 21% 29% 14% 3	180
December	1st to 10th	Day	26% 17% 32% 16% 9% 1	180
	11th to 20th	Day	26% 24% 32% 12% 3 2	180
	21st to end	Day	26% 29% 22% 16% 6% 1	198
January	1st to 10th	Night	24% 17% 31% 22% 5%	803
	11th to 20th	Night	25% 16% 26% 24% 7% 1	760
	21st to end	Night	16% 11% 32% 32% 8% 1	836
February	1st to 10th	Night	13% 17% 35% 27% 6% 1	760
	11th to 20th	Night	22% 16% 33% 22% 6%	743
	21st to end	Night	19% 17% 29% 27% 6% 1	628
March	1st to 10th	Night	23% 13% 33% 25% 6%	760
	11th to 20th	Night	24% 16% 30% 20% 9%	760
	21st to end	Night	22% 18% 29% 24% 6%	836
April	1st to 10th	Night	29% 13% 30% 21% 5% 1	760
	11th to 20th	Night	26% 14% 32% 22% 5%	626
	21st to end	Night	26% 13% 31% 24% 6%	570
May	1st to 10th	Night	30% 12% 30% 22% 6%	469
	11th to 20th	Night	23% 10% 32% 27% 8% 1	374
	21st to end	Night	27% 12% 30% 24% 7%	411
June	1st to 10th	Night	23% 6% 35% 30% 6%	380
	11th to 20th	Night	18% 10% 24% 36% 12% 1	380
	21st to end	Night	24% 7% 28% 32% 7% 1	380
July	1st to 10th	Night	25% 7% 27% 32% 9% 1	370
	11th to 20th	Night	19% 6% 20% 41% 13% 1	368
	21st to end	Night	20% 9% 20% 39% 12%	416
August	1st to 10th	Night	22% 4 21% 37% 16% 1	378
	11th to 20th	Night	22% 7% 21% 33% 16% 1	513
	21st to end	Night	22% 10% 21% 32% 14% 1	690
September	1st to 10th	Night	24% 11% 22% 30% 11% 1	760
	11th to 20th	Night	23% 10% 23% 29% 13% 2	760
	21st to end	Night	26% 11% 25% 27% 9% 2	760
October	1st to 10th	Night	26% 11% 24% 28% 10% 1	760
	11th to 20th	Night	38% 12% 21% 21% 8% 1	760
	21st to end	Night	38% 15% 20% 20% 6%	836
November	1st to 10th	Night	35% 16% 22% 20% 6% 1	780
	11th to 20th	Night	27% 20% 25% 21% 6%	804
	21st to end	Night	31% 19% 27% 17% 5% 1	850
December	1st to 10th	Night	32% 14% 25% 20% 8% 1	850
	11th to 20th	Night	27% 18% 26% 21% 7% 1	850
	21st to end	Night	25% 18% 27% 22% 8% 1	935

Page generated at 2024-11-08 06:44:49. Version ac07

Copyright © 2024 Attilla Danko.