Tadoussac
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tadoussac clear sky chart from 2005-11-06 to 2024-12-06.

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% 9% 3 7% 5% 5% 5% 4 6% 7% 33%	101932
	Night	16% 11% 4 9% 5% 4 4 4 5% 6% 31%	97840
Transparency	Day	48% 7% 15% 21% 8% 1	105380
	Night	52% 7% 13% 20% 8% 1	102482
Seeing	Day	21% 10% 28% 27% 12% 2	15762
	Night	22% 10% 28% 28% 11% 1	23911

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	15% 17% 6% 9% 5% 5% 4 3 5% 6% 25%	2252
	11th to 20th	Day	11% 12% 4 12% 7% 5% 6% 4 6% 6% 27%	2520
	21st to end	Day	8% 10% 6% 10% 7% 7% 4 4 6% 7% 30%	2772
February	1st to 10th	Day	7% 15% 5% 9% 7% 6% 6% 5% 6% 7% 26%	1558
	11th to 20th	Day	12% 13% 5% 10% 8% 5% 4 4 7% 7% 26%	1732
	21st to end	Day	13% 11% 3 9% 6% 5% 5% 4 6% 7% 32%	1570
March	1st to 10th	Day	15% 10% 3 6% 6% 5% 6% 4 7% 7% 32%	3116
	11th to 20th	Day	16% 17% 4 8% 5% 4 5% 4 6% 6% 24%	3411
	21st to end	Day	15% 15% 4 9% 4 4 4 3 4 6% 33%	3928
April	1st to 10th	Day	19% 11% 4 7% 4 4 5% 4 6% 7% 29%	2280
	11th to 20th	Day	18% 9% 2 6% 5% 4 5% 3 4 7% 37%	2428
	21st to end	Day	22% 9% 2 7% 4 4 5% 3 4 6% 34%	2470
May	1st to 10th	Day	15% 9% 3 7% 5% 4 5% 3 5% 7% 37%	4155
	11th to 20th	Day	17% 8% 3 6% 4 4 4 4 5% 6% 38%	4483
	21st to end	Day	17% 7% 4 8% 5% 5% 5% 5% 6% 8% 31%	5185
June	1st to 10th	Day	19% 8% 3 8% 5% 5% 4 4 5% 7% 32%	2850
	11th to 20th	Day	17% 7% 2 6% 5% 4 5% 4 6% 7% 37%	2850
	21st to end	Day	21% 8% 3 8% 5% 4 4 5% 5% 8% 30%	2850
July	1st to 10th	Day	14% 7% 3 7% 5% 5% 6% 5% 7% 9% 33%	4760
	11th to 20th	Day	12% 6% 2 8% 5% 6% 6% 6% 7% 8% 33%	4614
	21st to end	Day	10% 5% 2 7% 5% 5% 5% 5% 7% 8% 42%	4814
August	1st to 10th	Day	12% 6% 2 6% 5% 6% 6% 6% 8% 9% 35%	4341
	11th to 20th	Day	16% 7% 3 8% 6% 6% 6% 5% 8% 7% 29%	4045
	21st to end	Day	15% 5% 2 6% 5% 5% 5% 5% 7% 8% 37%	4532
September	1st to 10th	Day	15% 6% 3 6% 4 5% 6% 4 5% 8% 39%	2257
	11th to 20th	Day	16% 5% 2 6% 3 3 4 3 6% 6% 47%	2090
	21st to end	Day	17% 7% 2 6% 4 4 3 4 5% 7% 42%	2090
October	1st to 10th	Day	17% 7% 3 7% 4 4 5% 4 5% 8% 35%	2043
	11th to 20th	Day	20% 8% 3 8% 5% 6% 5% 4 6% 7% 29%	1770
	21st to end	Day	24% 10% 4 6% 4 5% 4 3 4 7% 28%	1881
November	1st to 10th	Day	16% 13% 2 9% 6% 5% 6% 4 5% 7% 28%	1761
	11th to 20th	Day	18% 12% 4 8% 6% 5% 5% 4 6% 6% 26%	1634
	21st to end	Day	21% 13% 5% 7% 5% 5% 5% 4 5% 6% 25%	1426
December	1st to 10th	Day	19% 16% 4 8% 6% 4 5% 4 6% 7% 23%	1365
	11th to 20th	Day	18% 17% 3 7% 7% 4 4 3 4 6% 29%	1668
	21st to end	Day	21% 13% 4 8% 4 3 3 3 3 4 33%	2431
January	1st to 10th	Night	12% 17% 6% 13% 7% 5% 5% 3 4 4 24%	4687
	11th to 20th	Night	11% 14% 6% 13% 7% 4 5% 3 6% 7% 25%	4440
	21st to end	Night	7% 14% 5% 10% 7% 6% 5% 4 7% 7% 27%	4884
February	1st to 10th	Night	9% 14% 5% 11% 7% 5% 4 3 5% 7% 29%	2622
	11th to 20th	Night	11% 14% 6% 12% 6% 5% 4 4 5% 8% 25%	2332
	21st to end	Night	13% 14% 6% 10% 6% 4 5% 3 5% 5% 31%	1884
March	1st to 10th	Night	16% 13% 5% 10% 6% 5% 5% 4 5% 6% 25%	3724
	11th to 20th	Night	15% 19% 5% 11% 7% 5% 4 3 4 5% 23%	3548
	21st to end	Night	17% 15% 4 9% 4 3 4 3 5% 6% 30%	3700
April	1st to 10th	Night	22% 13% 3 8% 5% 4 4 3 3 4 31%	1900
	11th to 20th	Night	20% 10% 2 6% 5% 4 3 3 6% 6% 34%	1701
	21st to end	Night	25% 9% 3 5% 3 3 3 4 5% 6% 34%	1710
May	1st to 10th	Night	20% 7% 2 6% 5% 4 5% 3 5% 7% 36%	2816
	11th to 20th	Night	18% 10% 2 7% 4 3 4 4 5% 7% 35%	2410
	21st to end	Night	18% 7% 3 7% 5% 5% 5% 4 6% 8% 31%	2401
June	1st to 10th	Night	19% 9% 3 8% 5% 4 6% 4 6% 6% 30%	1330
	11th to 20th	Night	17% 6% 2 5% 4 5% 5% 4 7% 7% 38%	1330
	21st to end	Night	23% 10% 3 6% 5% 4 5% 4 6% 7% 28%	1330
July	1st to 10th	Night	15% 7% 3 7% 5% 4 5% 5% 7% 9% 34%	2210
	11th to 20th	Night	12% 5% 3 8% 5% 5% 6% 6% 6% 9% 35%	2348
	21st to end	Night	11% 6% 2 6% 4 5% 5% 4 6% 8% 42%	2739
August	1st to 10th	Night	16% 6% 2 8% 6% 5% 5% 4 7% 7% 34%	2556
	11th to 20th	Night	15% 7% 3 10% 7% 6% 6% 5% 7% 8% 26%	2782
	21st to end	Night	17% 5% 2 6% 4 4 4 3 6% 7% 41%	3124
September	1st to 10th	Night	14% 7% 2 7% 5% 4 5% 3 4 7% 41%	1919
	11th to 20th	Night	18% 6% 2 5% 4 4 4 4 4 5% 43%	2090
	21st to end	Night	17% 8% 2 6% 3 4 4 3 5% 4 43%	2090
October	1st to 10th	Night	18% 7% 2 6% 4 4 4 3 5% 7% 41%	2137
	11th to 20th	Night	24% 7% 3 6% 4 5% 4 3 5% 6% 31%	2408
	21st to end	Night	24% 8% 3 6% 4 4 4 3 5% 7% 32%	2717
November	1st to 10th	Night	19% 11% 4 8% 5% 4 4 4 4 6% 32%	2537
	11th to 20th	Night	20% 11% 3 8% 5% 4 4 4 5% 5% 31%	2765
	21st to end	Night	20% 15% 5% 8% 5% 5% 4 3 5% 6% 23%	2970
December	1st to 10th	Night	18% 15% 5% 10% 5% 4 4 3 5% 6% 25%	2932
	11th to 20th	Night	20% 13% 4 9% 5% 4 4 4 5% 6% 26%	3531
	21st to end	Night	17% 13% 4 10% 6% 4 4 3 4 5% 29%	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	59% 6% 13% 17% 5%	2253
	11th to 20th	Day	55% 7% 11% 20% 5% 1	2520
	21st to end	Day	50% 8% 13% 20% 9%	2772
February	1st to 10th	Day	53% 8% 12% 16% 9% 2	1558
	11th to 20th	Day	58% 6% 10% 16% 10%	1740
	21st to end	Day	51% 6% 10% 20% 12% 2	1570
March	1st to 10th	Day	49% 7% 19% 13% 10% 3	3119
	11th to 20th	Day	58% 8% 13% 14% 6% 1	3411
	21st to end	Day	52% 5% 9% 20% 12% 3	3928
April	1st to 10th	Day	54% 6% 10% 19% 9% 2	2280
	11th to 20th	Day	46% 5% 12% 25% 10% 2	2428
	21st to end	Day	52% 5% 10% 18% 14% 2	2470
May	1st to 10th	Day	45% 6% 17% 19% 12% 1	4169
	11th to 20th	Day	45% 7% 15% 24% 8% 1	4487
	21st to end	Day	48% 8% 11% 24% 9% 1	5185
June	1st to 10th	Day	51% 7% 11% 20% 11% 1	2850
	11th to 20th	Day	46% 6% 15% 20% 11% 1	2850
	21st to end	Day	52% 8% 14% 17% 8% 1	2850
July	1st to 10th	Day	43% 8% 17% 26% 6%	4685
	11th to 20th	Day	43% 10% 21% 21% 5%	4533
	21st to end	Day	38% 9% 21% 25% 7%	4661
August	1st to 10th	Day	41% 9% 22% 22% 6%	4327
	11th to 20th	Day	49% 11% 18% 18% 3	4084
	21st to end	Day	41% 9% 19% 22% 9%	4532
September	1st to 10th	Day	41% 8% 17% 24% 10%	2257
	11th to 20th	Day	37% 6% 19% 28% 9% 1	2090
	21st to end	Day	42% 6% 17% 25% 9%	2090
October	1st to 10th	Day	51% 6% 16% 20% 6%	3394
	11th to 20th	Day	46% 7% 19% 26% 2	2921
	21st to end	Day	47% 8% 18% 21% 7%	3081
November	1st to 10th	Day	55% 6% 14% 19% 5%	1761
	11th to 20th	Day	56% 6% 12% 19% 5%	1634
	21st to end	Day	58% 7% 13% 15% 6%	1426
December	1st to 10th	Day	60% 7% 13% 15% 6%	1365
	11th to 20th	Day	58% 5% 7% 20% 10%	1668
	21st to end	Day	55% 5% 14% 17% 5% 4	2431
January	1st to 10th	Night	63% 6% 9% 13% 8%	4687
	11th to 20th	Night	56% 7% 12% 18% 7%	4440
	21st to end	Night	53% 8% 12% 19% 8%	4884
February	1st to 10th	Night	54% 6% 9% 18% 12% 1	2622
	11th to 20th	Night	58% 6% 10% 18% 8%	2335
	21st to end	Night	55% 6% 8% 22% 9% 1	1884
March	1st to 10th	Night	57% 7% 12% 16% 7% 1	3734
	11th to 20th	Night	62% 7% 9% 15% 7% 1	3549
	21st to end	Night	55% 5% 10% 19% 10% 1	3700
April	1st to 10th	Night	58% 5% 6% 16% 13% 2	1900
	11th to 20th	Night	50% 5% 9% 21% 14% 1	1701
	21st to end	Night	51% 5% 9% 20% 13% 2	1710
May	1st to 10th	Night	46% 7% 14% 18% 13% 1	2822
	11th to 20th	Night	47% 7% 14% 21% 10% 1	2411
	21st to end	Night	45% 10% 10% 22% 11% 1	2402
June	1st to 10th	Night	52% 5% 12% 20% 9% 2	1330
	11th to 20th	Night	43% 7% 13% 20% 13% 3	1330
	21st to end	Night	54% 6% 12% 17% 10%	1330
July	1st to 10th	Night	44% 8% 18% 25% 6%	2175
	11th to 20th	Night	42% 9% 20% 24% 4	2306
	21st to end	Night	38% 7% 23% 21% 10%	2651
August	1st to 10th	Night	46% 8% 17% 22% 6%	2546
	11th to 20th	Night	52% 11% 18% 13% 5%	2809
	21st to end	Night	41% 6% 14% 29% 9%	3124
September	1st to 10th	Night	43% 7% 14% 26% 10% 1	1919
	11th to 20th	Night	43% 5% 17% 25% 10% 1	2090
	21st to end	Night	43% 6% 13% 26% 12%	2090
October	1st to 10th	Night	46% 5% 11% 29% 8% 1	3566
	11th to 20th	Night	48% 7% 13% 29% 3	3996
	21st to end	Night	48% 7% 17% 21% 7%	4467
November	1st to 10th	Night	52% 6% 14% 19% 8%	2537
	11th to 20th	Night	53% 6% 13% 20% 7%	2765
	21st to end	Night	61% 6% 10% 15% 6%	2970
December	1st to 10th	Night	60% 5% 13% 16% 6%	2932
	11th to 20th	Night	56% 8% 10% 19% 8%	3532
	21st to end	Night	57% 5% 13% 16% 8% 2	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	24% 14% 36% 19% 6% 1	180
	11th to 20th	Day	23% 19% 34% 17% 6% 2	180
	21st to end	Day	14% 19% 29% 28% 9% 2	198
February	1st to 10th	Day	18% 16% 33% 26% 6% 2	218
	11th to 20th	Day	19% 19% 37% 18% 6% 1	399
	21st to end	Day	18% 18% 36% 21% 6% 1	382
March	1st to 10th	Day	25% 13% 32% 22% 8% 1	460
	11th to 20th	Day	21% 16% 29% 22% 10% 1	460
	21st to end	Day	26% 14% 31% 21% 6% 2	506
April	1st to 10th	Day	26% 16% 29% 22% 6% 2	460
	11th to 20th	Day	21% 10% 33% 26% 8% 2	452
	21st to end	Day	24% 12% 33% 21% 8% 2	460
May	1st to 10th	Day	24% 10% 26% 26% 11% 2	463
	11th to 20th	Day	20% 8% 28% 29% 12% 3	533
	21st to end	Day	22% 9% 30% 27% 8% 3	735
June	1st to 10th	Day	24% 6% 26% 30% 11% 3	680
	11th to 20th	Day	19% 5% 27% 29% 17% 4	680
	21st to end	Day	22% 6% 24% 34% 13% 2	680
July	1st to 10th	Day	19% 5% 23% 37% 14% 2	670
	11th to 20th	Day	14% 4 24% 37% 18% 2	587
	21st to end	Day	13% 5% 22% 39% 19% 2	532
August	1st to 10th	Day	16% 4 20% 38% 17% 4	486
	11th to 20th	Day	16% 4 20% 38% 20% 3	479
	21st to end	Day	15% 8% 24% 31% 19% 4	539
September	1st to 10th	Day	17% 8% 27% 27% 17% 4	490
	11th to 20th	Day	18% 6% 26% 34% 12% 4	490
	21st to end	Day	19% 6% 27% 30% 14% 4	490
October	1st to 10th	Day	19% 9% 31% 25% 13% 3	465
	11th to 20th	Day	26% 11% 28% 19% 13% 2	390
	21st to end	Day	30% 14% 24% 24% 7% 1	429
November	1st to 10th	Day	24% 16% 31% 22% 7% 1	395
	11th to 20th	Day	27% 11% 32% 18% 11% 1	400
	21st to end	Day	31% 15% 30% 19% 5%	226
December	1st to 10th	Day	25% 12% 33% 22% 7% 2	190
	11th to 20th	Day	27% 17% 36% 14% 4 2	180
	21st to end	Day	28% 21% 29% 18% 5%	198
January	1st to 10th	Night	22% 15% 34% 24% 5% 1	833
	11th to 20th	Night	21% 14% 39% 21% 5%	760
	21st to end	Night	15% 13% 38% 27% 7% 1	836
February	1st to 10th	Night	16% 13% 38% 25% 7% 1	760
	11th to 20th	Night	20% 17% 36% 21% 6%	743
	21st to end	Night	20% 12% 35% 24% 8% 1	628
March	1st to 10th	Night	19% 11% 34% 29% 5% 1	760
	11th to 20th	Night	21% 15% 32% 22% 9% 1	760
	21st to end	Night	22% 11% 31% 28% 7% 1	836
April	1st to 10th	Night	28% 11% 28% 25% 9% 1	760
	11th to 20th	Night	24% 8% 32% 25% 11% 1	577
	21st to end	Night	29% 9% 26% 26% 9% 2	570
May	1st to 10th	Night	27% 5% 24% 31% 12% 1	565
	11th to 20th	Night	24% 5% 24% 32% 14% 1	374
	21st to end	Night	21% 5% 31% 30% 11% 2	411
June	1st to 10th	Night	23% 4 18% 39% 13% 3	380
	11th to 20th	Night	19% 2 18% 35% 23% 2	380
	21st to end	Night	26% 6% 18% 33% 16% 1	380
July	1st to 10th	Night	18% 3 20% 40% 17% 2	370
	11th to 20th	Night	13% 2 17% 47% 20% 1	368
	21st to end	Night	16% 3 15% 42% 21% 3	416
August	1st to 10th	Night	16% 3 15% 37% 27% 2	402
	11th to 20th	Night	19% 4 15% 38% 23% 2	562
	21st to end	Night	16% 4 18% 36% 22% 4	627
September	1st to 10th	Night	17% 5% 23% 36% 16% 3	751
	11th to 20th	Night	23% 3 22% 33% 16% 4	760
	21st to end	Night	21% 4 24% 33% 16% 2	760
October	1st to 10th	Night	22% 6% 26% 32% 12% 3	760
	11th to 20th	Night	27% 8% 24% 26% 13% 1	760
	21st to end	Night	28% 10% 26% 27% 8%	836
November	1st to 10th	Night	24% 12% 29% 26% 8%	780
	11th to 20th	Night	27% 13% 31% 20% 8% 1	883
	21st to end	Night	27% 14% 28% 24% 6% 1	900
December	1st to 10th	Night	23% 15% 33% 22% 6% 1	878
	11th to 20th	Night	24% 18% 32% 20% 6%	850
	21st to end	Night	24% 16% 33% 21% 5% 1	935

Page generated at 2024-12-03 06:45:14. Version ac07

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