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 2024-01-16.

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% 9% 4 6% 6% 3 5% 5% 5% 7% 33%	74603
	Night	17% 10% 4 7% 6% 3 5% 4 5% 6% 31%	75206
Transparency	Day	49% 7% 14% 20% 9% 1	74296
	Night	52% 6% 12% 19% 9% 1	75048
Seeing	Day	21% 10% 28% 27% 12% 2	14533
	Night	22% 10% 28% 28% 11% 1	22822

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	16% 17% 6% 9% 7% 4 5% 3 5% 6% 23%	1360
	11th to 20th	Day	12% 14% 6% 10% 7% 3 7% 4 5% 5% 25%	1480
	21st to end	Day	10% 10% 6% 8% 7% 5% 5% 6% 6% 8% 30%	1584
February	1st to 10th	Day	6% 14% 6% 8% 8% 5% 6% 6% 6% 8% 26%	1476
	11th to 20th	Day	13% 13% 5% 9% 9% 4 4 4 6% 7% 26%	1639
	21st to end	Day	13% 10% 4 9% 6% 4 5% 5% 6% 7% 32%	1480
March	1st to 10th	Day	16% 11% 6% 5% 6% 4 5% 5% 6% 6% 31%	1797
	11th to 20th	Day	15% 12% 5% 8% 6% 3 5% 4 5% 6% 31%	1939
	21st to end	Day	16% 12% 4 7% 5% 3 5% 5% 4 6% 32%	2236
April	1st to 10th	Day	20% 10% 4 7% 5% 3 5% 5% 6% 8% 28%	2160
	11th to 20th	Day	18% 8% 2 5% 5% 3 4 4 4 7% 38%	2298
	21st to end	Day	22% 9% 3 6% 4 3 5% 4 4 6% 33%	2340
May	1st to 10th	Day	21% 8% 3 6% 5% 3 5% 4 5% 6% 35%	2361
	11th to 20th	Day	18% 7% 3 6% 5% 3 5% 5% 5% 6% 38%	2521
	21st to end	Day	19% 6% 3 5% 5% 2 5% 5% 5% 8% 36%	2919
June	1st to 10th	Day	19% 7% 4 7% 6% 4 5% 5% 5% 7% 31%	2700
	11th to 20th	Day	18% 7% 3 5% 5% 3 5% 5% 6% 7% 37%	2700
	21st to end	Day	21% 7% 4 7% 5% 3 4 6% 5% 8% 30%	2700
July	1st to 10th	Day	15% 7% 3 5% 5% 4 6% 6% 7% 10% 32%	2700
	11th to 20th	Day	13% 6% 3 6% 6% 4 6% 6% 6% 8% 36%	2624
	21st to end	Day	12% 6% 2 6% 6% 3 6% 7% 7% 8% 37%	2744
August	1st to 10th	Day	14% 6% 3 5% 6% 4 6% 7% 8% 9% 32%	2465
	11th to 20th	Day	13% 6% 2 5% 6% 3 6% 6% 8% 7% 38%	2304
	21st to end	Day	12% 5% 2 5% 6% 4 5% 6% 8% 10% 36%	2574
September	1st to 10th	Day	15% 5% 4 5% 5% 3 6% 6% 5% 8% 38%	2139
	11th to 20th	Day	17% 5% 2 5% 5% 2 3 4 6% 6% 45%	1980
	21st to end	Day	18% 6% 2 4 5% 3 4 4 5% 7% 43%	1980
October	1st to 10th	Day	17% 7% 3 6% 5% 4 5% 4 5% 8% 36%	1936
	11th to 20th	Day	21% 7% 3 7% 6% 5% 5% 6% 6% 7% 28%	1677
	21st to end	Day	25% 10% 4 6% 5% 4 4 4 4 6% 27%	1782
November	1st to 10th	Day	16% 11% 3 8% 6% 4 6% 6% 5% 7% 28%	1671
	11th to 20th	Day	18% 11% 4 7% 6% 3 5% 5% 6% 7% 26%	1553
	21st to end	Day	20% 12% 5% 6% 6% 4 5% 5% 5% 6% 26%	1355
December	1st to 10th	Day	20% 13% 5% 7% 7% 4 5% 5% 6% 6% 23%	1330
	11th to 20th	Day	18% 15% 4 6% 7% 3 4 3 4 6% 29%	1668
	21st to end	Day	21% 13% 4 7% 5% 3 3 3 3 4 33%	2431
January	1st to 10th	Night	15% 17% 6% 10% 7% 4 6% 4 5% 5% 21%	2803
	11th to 20th	Night	14% 14% 5% 11% 7% 3 5% 4 6% 7% 25%	2602
	21st to end	Night	9% 12% 5% 9% 8% 4 5% 5% 8% 9% 27%	2772
February	1st to 10th	Night	10% 12% 6% 9% 8% 3 5% 4 5% 7% 29%	2484
	11th to 20th	Night	12% 14% 7% 11% 7% 4 5% 4 4 8% 25%	2205
	21st to end	Night	13% 12% 7% 10% 6% 3 4 4 4 5% 31%	1776
March	1st to 10th	Night	13% 11% 6% 8% 6% 4 4 4 6% 7% 29%	2150
	11th to 20th	Night	13% 15% 5% 7% 7% 4 3 4 4 7% 30%	2020
	21st to end	Night	15% 12% 4 6% 6% 3 5% 4 5% 6% 34%	2116
April	1st to 10th	Night	23% 12% 3 7% 6% 4 5% 4 3 4 30%	1800
	11th to 20th	Night	20% 9% 3 5% 6% 3 3 4 6% 6% 35%	1611
	21st to end	Night	26% 8% 3 4 3 2 3 5% 5% 6% 34%	1620
May	1st to 10th	Night	25% 7% 3 6% 6% 3 5% 4 5% 5% 31%	1616
	11th to 20th	Night	20% 9% 3 5% 5% 2 4 4 4 6% 38%	1369
	21st to end	Night	19% 8% 4 6% 5% 3 4 5% 5% 6% 34%	1356
June	1st to 10th	Night	20% 8% 3 8% 6% 3 6% 4 6% 6% 30%	1260
	11th to 20th	Night	18% 6% 2 4 4 4 5% 5% 7% 7% 38%	1260
	21st to end	Night	24% 9% 3 6% 6% 3 4 6% 6% 7% 29%	1260
July	1st to 10th	Night	19% 7% 3 6% 5% 3 5% 5% 7% 9% 33%	1260
	11th to 20th	Night	12% 6% 3 7% 6% 4 7% 7% 6% 9% 35%	1333
	21st to end	Night	14% 7% 3 6% 6% 4 6% 5% 6% 8% 33%	1574
August	1st to 10th	Night	13% 6% 2 6% 7% 4 6% 5% 8% 8% 36%	1454
	11th to 20th	Night	16% 6% 3 6% 7% 4 6% 7% 7% 8% 32%	1596
	21st to end	Night	14% 5% 3 5% 5% 3 5% 5% 6% 9% 39%	1782
September	1st to 10th	Night	15% 7% 2 7% 5% 4 5% 5% 4 7% 40%	1817
	11th to 20th	Night	19% 6% 2 4 5% 4 4 4 4 5% 42%	1980
	21st to end	Night	18% 7% 2 5% 4 3 4 4 4 5% 44%	1980
October	1st to 10th	Night	17% 7% 2 5% 5% 3 4 4 5% 7% 41%	2024
	11th to 20th	Night	24% 7% 4 6% 5% 4 4 4 5% 6% 31%	2281
	21st to end	Night	24% 8% 3 6% 5% 3 4 4 4 7% 32%	2574
November	1st to 10th	Night	19% 10% 4 7% 6% 3 4 5% 4 6% 32%	2407
	11th to 20th	Night	19% 10% 4 7% 5% 3 4 5% 5% 6% 31%	2626
	21st to end	Night	19% 13% 5% 8% 6% 3 5% 4 5% 6% 24%	2821
December	1st to 10th	Night	19% 14% 5% 9% 5% 3 5% 4 5% 6% 25%	2850
	11th to 20th	Night	20% 12% 4 8% 5% 3 5% 4 5% 6% 27%	3531
	21st to end	Night	17% 12% 5% 9% 7% 3 4 4 4 5% 30%	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	62% 5% 10% 15% 7%	1361
	11th to 20th	Day	60% 7% 8% 17% 6% 2	1480
	21st to end	Day	50% 6% 10% 19% 13%	1584
February	1st to 10th	Day	53% 8% 12% 15% 10% 2	1476
	11th to 20th	Day	58% 6% 10% 16% 9%	1647
	21st to end	Day	51% 5% 9% 21% 13% 1	1480
March	1st to 10th	Day	52% 6% 12% 14% 14% 2	1800
	11th to 20th	Day	53% 6% 10% 19% 11% 1	1939
	21st to end	Day	52% 5% 10% 20% 12% 2	2236
April	1st to 10th	Day	55% 6% 10% 18% 10% 2	2160
	11th to 20th	Day	46% 4 12% 26% 10% 2	2298
	21st to end	Day	53% 5% 9% 18% 13% 2	2340
May	1st to 10th	Day	49% 5% 13% 18% 13% 2	2361
	11th to 20th	Day	46% 6% 12% 23% 12% 1	2525
	21st to end	Day	47% 6% 12% 23% 11% 1	2919
June	1st to 10th	Day	51% 7% 12% 19% 11% 1	2700
	11th to 20th	Day	47% 6% 14% 21% 11% 1	2700
	21st to end	Day	52% 8% 14% 17% 8% 1	2700
July	1st to 10th	Day	44% 9% 19% 22% 7%	2625
	11th to 20th	Day	44% 8% 18% 23% 8% 1	2543
	21st to end	Day	42% 10% 19% 22% 7%	2591
August	1st to 10th	Day	44% 10% 23% 18% 5%	2451
	11th to 20th	Day	41% 10% 20% 23% 6%	2304
	21st to end	Day	39% 9% 21% 24% 7%	2574
September	1st to 10th	Day	41% 8% 17% 23% 10%	2139
	11th to 20th	Day	38% 6% 19% 27% 9% 1	1980
	21st to end	Day	41% 6% 17% 25% 9%	1980
October	1st to 10th	Day	45% 6% 16% 21% 11% 1	1936
	11th to 20th	Day	54% 8% 15% 20% 3	1677
	21st to end	Day	58% 6% 13% 16% 7%	1782
November	1st to 10th	Day	55% 6% 14% 19% 5%	1671
	11th to 20th	Day	56% 7% 13% 19% 5%	1553
	21st to end	Day	57% 8% 14% 16% 6%	1355
December	1st to 10th	Day	60% 7% 12% 15% 6%	1330
	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	65% 6% 9% 13% 6%	2803
	11th to 20th	Night	58% 7% 10% 17% 7% 1	2602
	21st to end	Night	52% 8% 9% 21% 10% 1	2772
February	1st to 10th	Night	54% 6% 10% 18% 12% 1	2484
	11th to 20th	Night	59% 6% 10% 17% 8%	2208
	21st to end	Night	56% 5% 8% 22% 9% 1	1776
March	1st to 10th	Night	53% 6% 11% 20% 10% 1	2160
	11th to 20th	Night	55% 4 9% 18% 12% 2	2021
	21st to end	Night	50% 6% 9% 21% 13% 2	2116
April	1st to 10th	Night	59% 5% 7% 15% 13% 2	1800
	11th to 20th	Night	49% 5% 9% 21% 15% 1	1611
	21st to end	Night	51% 5% 8% 20% 13% 2	1620
May	1st to 10th	Night	55% 5% 8% 17% 13% 2	1616
	11th to 20th	Night	47% 4 11% 23% 12% 2	1370
	21st to end	Night	51% 7% 9% 17% 14% 2	1357
June	1st to 10th	Night	53% 5% 11% 20% 9% 2	1260
	11th to 20th	Night	44% 7% 12% 20% 13% 3	1260
	21st to end	Night	54% 6% 12% 17% 10%	1260
July	1st to 10th	Night	47% 7% 17% 23% 6%	1225
	11th to 20th	Night	43% 10% 17% 22% 8% 1	1291
	21st to end	Night	48% 8% 16% 19% 8%	1486
August	1st to 10th	Night	42% 10% 20% 23% 5%	1444
	11th to 20th	Night	47% 10% 17% 19% 7% 1	1596
	21st to end	Night	40% 7% 17% 27% 8%	1782
September	1st to 10th	Night	43% 7% 14% 25% 10% 1	1817
	11th to 20th	Night	44% 5% 16% 24% 10% 1	1980
	21st to end	Night	42% 6% 13% 26% 12% 1	1980
October	1st to 10th	Night	43% 5% 14% 24% 12% 1	2024
	11th to 20th	Night	53% 7% 12% 23% 4	2281
	21st to end	Night	53% 6% 14% 19% 7%	2574
November	1st to 10th	Night	52% 6% 14% 19% 8%	2407
	11th to 20th	Night	53% 7% 13% 20% 7%	2626
	21st to end	Night	60% 6% 11% 15% 7%	2821
December	1st to 10th	Night	60% 5% 12% 16% 6%	2850
	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	24% 20% 32% 17% 6% 2	170
	21st to end	Day	15% 18% 28% 29% 8% 1	176
February	1st to 10th	Day	18% 17% 34% 25% 5% 1	196
	11th to 20th	Day	20% 19% 36% 17% 7% 1	366
	21st to end	Day	17% 18% 35% 22% 7% 1	346
March	1st to 10th	Day	26% 14% 31% 20% 8% 1	420
	11th to 20th	Day	20% 16% 30% 22% 10% 1	420
	21st to end	Day	24% 13% 32% 23% 6% 2	462
April	1st to 10th	Day	26% 16% 30% 21% 6% 2	420
	11th to 20th	Day	21% 10% 33% 25% 8% 2	412
	21st to end	Day	25% 11% 32% 21% 9% 2	420
May	1st to 10th	Day	26% 10% 27% 25% 10% 2	423
	11th to 20th	Day	20% 9% 30% 28% 11% 3	490
	21st to end	Day	23% 9% 29% 28% 9% 3	680
June	1st to 10th	Day	24% 6% 27% 30% 10% 3	630
	11th to 20th	Day	20% 4 26% 30% 16% 3	630
	21st to end	Day	21% 5% 22% 35% 14% 2	630
July	1st to 10th	Day	19% 4 23% 36% 15% 3	620
	11th to 20th	Day	15% 4 23% 36% 19% 2	542
	21st to end	Day	13% 5% 21% 40% 19% 2	488
August	1st to 10th	Day	16% 4 20% 38% 18% 4	446
	11th to 20th	Day	15% 4 21% 37% 20% 3	439
	21st to end	Day	15% 8% 24% 32% 18% 4	495
September	1st to 10th	Day	17% 7% 28% 27% 18% 4	450
	11th to 20th	Day	19% 7% 27% 33% 10% 4	450
	21st to end	Day	19% 6% 28% 30% 13% 4	450
October	1st to 10th	Day	18% 8% 32% 26% 13% 4	428
	11th to 20th	Day	27% 9% 28% 20% 14% 2	360
	21st to end	Day	31% 13% 25% 23% 7% 1	396
November	1st to 10th	Day	23% 16% 31% 22% 7% 1	365
	11th to 20th	Day	27% 10% 33% 18% 11% 1	370
	21st to end	Day	29% 15% 30% 20% 6%	205
December	1st to 10th	Day	26% 12% 33% 19% 8% 2	180
	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% 38% 21% 5%	744
	21st to end	Night	16% 13% 38% 27% 7% 1	792
February	1st to 10th	Night	17% 14% 38% 24% 7%	720
	11th to 20th	Night	21% 17% 36% 20% 6%	703
	21st to end	Night	20% 12% 35% 24% 8% 1	592
March	1st to 10th	Night	19% 11% 34% 28% 6% 1	720
	11th to 20th	Night	20% 15% 33% 21% 10% 1	720
	21st to end	Night	21% 10% 31% 29% 7% 1	792
April	1st to 10th	Night	28% 10% 28% 25% 8% 1	720
	11th to 20th	Night	24% 7% 32% 25% 10% 1	547
	21st to end	Night	30% 8% 26% 25% 9% 2	540
May	1st to 10th	Night	27% 5% 23% 31% 13% 1	536
	11th to 20th	Night	24% 5% 25% 33% 12% 1	354
	21st to end	Night	22% 4 32% 29% 11% 2	389
June	1st to 10th	Night	23% 4 19% 40% 12% 2	360
	11th to 20th	Night	20% 2 17% 36% 23% 2	360
	21st to end	Night	26% 6% 17% 33% 16% 1	360
July	1st to 10th	Night	19% 3 20% 40% 17% 2	350
	11th to 20th	Night	13% 1 16% 47% 21% 1	348
	21st to end	Night	17% 3 15% 41% 22% 3	394
August	1st to 10th	Night	16% 3 14% 38% 28% 2	380
	11th to 20th	Night	19% 4 14% 38% 22% 2	532
	21st to end	Night	15% 4 18% 37% 22% 4	594
September	1st to 10th	Night	18% 4 23% 36% 17% 3	711
	11th to 20th	Night	24% 3 23% 32% 15% 3	720
	21st to end	Night	21% 3 25% 33% 16% 2	720
October	1st to 10th	Night	21% 6% 27% 32% 12% 3	720
	11th to 20th	Night	27% 8% 24% 26% 13% 2	720
	21st to end	Night	28% 9% 26% 27% 9% 1	792
November	1st to 10th	Night	24% 11% 29% 27% 9%	740
	11th to 20th	Night	26% 13% 31% 20% 8% 1	834
	21st to end	Night	26% 14% 28% 24% 6% 1	850
December	1st to 10th	Night	24% 15% 33% 22% 6% 1	850
	11th to 20th	Night	24% 18% 32% 20% 6%	850
	21st to end	Night	24% 16% 33% 21% 5% 1	935

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