Shawinigan
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Shawinigan clear sky chart from 2005-11-06 to 2026-03-18.

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	18% 10% 3 8% 5% 5% 5% 4 5% 6% 31%	130841
	Night	17% 11% 4 9% 5% 4 4 3 5% 6% 31%	130653
Transparency	Day	53% 4 12% 20% 10% 1	134273
	Night	55% 3 11% 20% 10% 1	135309
Seeing	Day	24% 12% 31% 22% 9% 2	16145
	Night	24% 9% 29% 29% 9% 1	25285

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	14% 15% 6% 12% 5% 5% 5% 3 4 5% 26%	4661
	11th to 20th	Day	12% 16% 7% 15% 7% 5% 5% 3 4 5% 22%	4650
	21st to end	Day	8% 11% 7% 12% 6% 5% 5% 4 6% 6% 31%	5124
February	1st to 10th	Day	12% 16% 5% 11% 7% 5% 4 3 3 5% 28%	1754
	11th to 20th	Day	13% 16% 5% 10% 6% 4 4 4 5% 5% 28%	1976
	21st to end	Day	14% 15% 5% 11% 6% 5% 5% 3 4 5% 28%	1730
March	1st to 10th	Day	22% 14% 4 9% 6% 5% 3 3 3 4 26%	4576
	11th to 20th	Day	12% 14% 4 10% 5% 4 5% 4 5% 6% 32%	4717
	21st to end	Day	17% 14% 4 8% 5% 4 4 3 3 4 33%	5970
April	1st to 10th	Day	22% 13% 3 7% 4 4 3 3 4 5% 31%	2400
	11th to 20th	Day	21% 8% 2 7% 4 4 4 3 4 5% 36%	2404
	21st to end	Day	22% 10% 3 7% 4 5% 4 4 5% 6% 30%	2600
May	1st to 10th	Day	28% 9% 2 7% 4 4 4 3 4 6% 29%	6207
	11th to 20th	Day	21% 8% 3 7% 4 4 4 3 5% 8% 34%	6318
	21st to end	Day	22% 9% 3 7% 5% 5% 5% 4 5% 6% 30%	6949
June	1st to 10th	Day	21% 8% 3 8% 5% 6% 5% 4 6% 7% 29%	2800
	11th to 20th	Day	17% 7% 2 7% 5% 5% 5% 5% 7% 8% 34%	2800
	21st to end	Day	22% 9% 3 8% 5% 5% 5% 4 5% 7% 28%	2800
July	1st to 10th	Day	15% 6% 3 8% 5% 5% 6% 5% 7% 8% 30%	6360
	11th to 20th	Day	14% 6% 3 7% 5% 6% 6% 5% 7% 9% 32%	6360
	21st to end	Day	11% 5% 2 6% 4 5% 5% 4 7% 9% 42%	6926
August	1st to 10th	Day	14% 5% 2 7% 6% 6% 6% 5% 8% 9% 31%	4563
	11th to 20th	Day	18% 6% 2 6% 5% 4 5% 5% 7% 9% 33%	4250
	21st to end	Day	18% 6% 2 6% 4 4 5% 3 6% 8% 38%	4313
September	1st to 10th	Day	14% 5% 2 5% 5% 4 4 4 6% 8% 42%	2400
	11th to 20th	Day	14% 6% 2 5% 3 3 4 3 5% 8% 46%	2280
	21st to end	Day	21% 7% 3 5% 3 3 3 3 5% 6% 40%	2200
October	1st to 10th	Day	20% 7% 3 6% 4 4 4 3 4 8% 36%	2114
	11th to 20th	Day	21% 8% 2 9% 6% 5% 4 4 5% 6% 28%	1895
	21st to end	Day	26% 11% 3 7% 4 4 4 3 4 6% 28%	1980
November	1st to 10th	Day	17% 12% 3 6% 6% 5% 5% 4 4 6% 32%	1851
	11th to 20th	Day	20% 12% 4 7% 6% 4 4 3 4 6% 29%	1817
	21st to end	Day	21% 17% 4 7% 6% 4 4 3 4 5% 25%	1680
December	1st to 10th	Day	19% 17% 6% 10% 7% 5% 4 3 3 4 22%	2482
	11th to 20th	Day	19% 14% 4 9% 4 5% 4 3 4 5% 29%	2886
	21st to end	Day	19% 15% 4 9% 6% 4 4 3 4 4 26%	4048
January	1st to 10th	Night	13% 18% 6% 13% 7% 5% 4 3 5% 4 22%	8234
	11th to 20th	Night	11% 20% 7% 15% 7% 5% 5% 3 4 4 20%	8235
	21st to end	Night	8% 11% 5% 14% 8% 7% 5% 4 6% 6% 27%	9057
February	1st to 10th	Night	11% 15% 5% 10% 7% 5% 5% 3 5% 5% 30%	2862
	11th to 20th	Night	12% 15% 4 12% 7% 5% 4 3 4 5% 29%	2529
	21st to end	Night	15% 12% 5% 9% 5% 5% 5% 4 5% 4 32%	2076
March	1st to 10th	Night	23% 13% 3 12% 6% 4 5% 2 4 4 24%	5484
	11th to 20th	Night	15% 14% 4 9% 5% 5% 5% 4 6% 7% 28%	5392
	21st to end	Night	16% 11% 4 10% 5% 5% 5% 4 4 5% 31%	4962
April	1st to 10th	Night	22% 12% 3 7% 4 4 3 4 5% 5% 32%	2000
	11th to 20th	Night	20% 9% 3 6% 5% 3 4 3 5% 5% 36%	1945
	21st to end	Night	24% 9% 3 6% 4 3 4 3 5% 6% 35%	1800
May	1st to 10th	Night	26% 9% 3 7% 4 4 4 4 5% 6% 28%	3764
	11th to 20th	Night	24% 7% 2 6% 4 4 5% 3 5% 6% 34%	3575
	21st to end	Night	19% 9% 3 8% 6% 5% 4 3 5% 8% 30%	3926
June	1st to 10th	Night	21% 7% 2 6% 4 4 5% 4 6% 8% 35%	1600
	11th to 20th	Night	19% 7% 2 6% 4 5% 4 4 5% 8% 36%	1600
	21st to end	Night	20% 7% 3 7% 5% 4 4 4 6% 7% 33%	1600
July	1st to 10th	Night	13% 6% 2 7% 5% 6% 6% 5% 8% 9% 34%	3600
	11th to 20th	Night	16% 6% 2 6% 5% 4 5% 4 5% 8% 39%	3600
	21st to end	Night	11% 5% 2 5% 4 4 5% 4 6% 8% 45%	3926
August	1st to 10th	Night	14% 6% 2 7% 5% 5% 5% 5% 6% 7% 38%	2586
	11th to 20th	Night	17% 7% 3 6% 4 4 4 4 6% 6% 39%	2765
	21st to end	Night	18% 7% 3 8% 5% 4 4 3 4 6% 38%	3581
September	1st to 10th	Night	13% 5% 2 5% 5% 4 4 3 6% 6% 47%	2000
	11th to 20th	Night	14% 5% 2 5% 3 3 3 3 5% 6% 51%	2120
	21st to end	Night	18% 6% 2 5% 4 3 4 3 4 6% 45%	2200
October	1st to 10th	Night	18% 8% 2 6% 4 4 4 3 4 5% 42%	2284
	11th to 20th	Night	21% 8% 3 7% 4 3 4 3 4 6% 36%	2504
	21st to end	Night	25% 8% 3 7% 4 4 4 3 4 6% 31%	2860
November	1st to 10th	Night	19% 11% 4 7% 5% 4 4 3 5% 5% 33%	2667
	11th to 20th	Night	20% 10% 3 7% 5% 5% 5% 3 5% 6% 31%	2798
	21st to end	Night	23% 14% 4 7% 5% 4 4 3 4 5% 27%	2940
December	1st to 10th	Night	16% 14% 5% 10% 7% 5% 5% 4 5% 6% 23%	4912
	11th to 20th	Night	24% 12% 4 10% 5% 4 4 3 4 4 26%	5519
	21st to end	Night	22% 18% 6% 9% 3 3 3 2 3 3 28%	7150

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	63% 2 12% 17% 6%	4662
	11th to 20th	Day	67% 2 7% 15% 8% 1	4680
	21st to end	Day	55% 2 9% 20% 14% 1	5124
February	1st to 10th	Day	60% 2 9% 18% 9% 2	1754
	11th to 20th	Day	59% 2 12% 16% 11% 1	1985
	21st to end	Day	60% 3 8% 16% 10% 2	1730
March	1st to 10th	Day	64% 1 9% 11% 11% 3	4579
	11th to 20th	Day	54% 3 15% 15% 12% 1	4717
	21st to end	Day	56% 2 5% 19% 16% 3	5970
April	1st to 10th	Day	56% 3 9% 16% 13% 2	2400
	11th to 20th	Day	51% 3 9% 22% 13% 3	2404
	21st to end	Day	55% 3 9% 18% 13% 3	2600
May	1st to 10th	Day	58% 2 8% 19% 12% 1	6218
	11th to 20th	Day	51% 3 16% 20% 8% 2	6322
	21st to end	Day	56% 3 10% 16% 13% 3	6949
June	1st to 10th	Day	54% 4 10% 20% 10% 2	2800
	11th to 20th	Day	47% 4 12% 24% 12% 2	2800
	21st to end	Day	56% 5% 11% 18% 10% 1	2800
July	1st to 10th	Day	49% 6% 14% 24% 7%	6290
	11th to 20th	Day	44% 7% 17% 26% 6%	6285
	21st to end	Day	38% 5% 17% 31% 8%	6728
August	1st to 10th	Day	46% 7% 19% 21% 7%	4549
	11th to 20th	Day	46% 6% 20% 23% 6%	4291
	21st to end	Day	45% 5% 15% 21% 14% 1	4313
September	1st to 10th	Day	40% 3 18% 27% 11% 1	2400
	11th to 20th	Day	38% 3 16% 31% 11% 1	2280
	21st to end	Day	45% 4 13% 27% 11%	2200
October	1st to 10th	Day	48% 5% 12% 28% 7%	3439
	11th to 20th	Day	50% 5% 17% 24% 3	3059
	21st to end	Day	48% 4 20% 20% 7% 1	3180
November	1st to 10th	Day	55% 3 11% 21% 8% 1	1851
	11th to 20th	Day	58% 3 11% 19% 9%	1817
	21st to end	Day	62% 5% 10% 16% 5%	1680
December	1st to 10th	Day	67% 2 9% 17% 5%	2482
	11th to 20th	Day	59% 3 8% 18% 11%	2887
	21st to end	Day	62% 3 8% 16% 10%	4048
January	1st to 10th	Night	68% 2 10% 15% 5%	8234
	11th to 20th	Night	71% 2 7% 14% 5%	8280
	21st to end	Night	58% 2 9% 16% 14%	9057
February	1st to 10th	Night	57% 2 10% 19% 10% 1	2862
	11th to 20th	Night	60% 2 9% 17% 11% 1	2531
	21st to end	Night	56% 3 7% 19% 13% 2	2076
March	1st to 10th	Night	66% 1 8% 11% 11% 3	5494
	11th to 20th	Night	57% 3 12% 16% 10% 2	5393
	21st to end	Night	57% 2 5% 24% 10% 2	4962
April	1st to 10th	Night	55% 2 8% 18% 15% 2	2000
	11th to 20th	Night	49% 3 9% 23% 14% 2	1945
	21st to end	Night	51% 4 7% 21% 15% 3	1800
May	1st to 10th	Night	59% 2 9% 18% 10% 1	3770
	11th to 20th	Night	52% 2 14% 21% 10% 2	3576
	21st to end	Night	54% 3 11% 16% 15% 2	3927
June	1st to 10th	Night	48% 3 12% 22% 14% 1	1600
	11th to 20th	Night	47% 4 11% 21% 13% 4	1600
	21st to end	Night	50% 5% 12% 19% 14% 1	1600
July	1st to 10th	Night	46% 5% 20% 21% 7%	3560
	11th to 20th	Night	43% 5% 19% 26% 6%	3552
	21st to end	Night	36% 5% 18% 30% 11%	3809
August	1st to 10th	Night	45% 5% 17% 24% 9%	2576
	11th to 20th	Night	46% 5% 18% 23% 7%	2790
	21st to end	Night	48% 4 13% 24% 12%	3581
September	1st to 10th	Night	38% 4 16% 28% 13% 1	2000
	11th to 20th	Night	35% 3 18% 33% 10% 1	2120
	21st to end	Night	43% 3 11% 30% 13%	2200
October	1st to 10th	Night	49% 5% 13% 24% 9%	3739
	11th to 20th	Night	46% 4 16% 29% 5%	4079
	21st to end	Night	46% 3 18% 20% 11% 1	4610
November	1st to 10th	Night	54% 4 12% 22% 7% 1	2667
	11th to 20th	Night	55% 4 11% 21% 9% 1	2798
	21st to end	Night	62% 3 10% 17% 8%	2940
December	1st to 10th	Night	63% 3 13% 15% 5%	4912
	11th to 20th	Night	63% 2 7% 19% 9%	5519
	21st to end	Night	64% 1 7% 17% 10% 1	7150

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	29% 12% 36% 18% 5%	220
	11th to 20th	Day	29% 12% 34% 20% 5% 1	220
	21st to end	Day	17% 13% 38% 23% 10% 1	242
February	1st to 10th	Day	25% 19% 39% 14% 4	259
	11th to 20th	Day	25% 17% 38% 17% 3	464
	21st to end	Day	26% 14% 37% 18% 4	446
March	1st to 10th	Day	27% 16% 33% 19% 6%	540
	11th to 20th	Day	27% 16% 36% 16% 5% 1	528
	21st to end	Day	28% 18% 27% 19% 7% 2	550
April	1st to 10th	Day	31% 12% 29% 22% 6% 1	500
	11th to 20th	Day	29% 14% 30% 20% 5% 3	492
	21st to end	Day	29% 14% 37% 13% 5% 1	500
May	1st to 10th	Day	29% 12% 33% 18% 6% 1	503
	11th to 20th	Day	21% 13% 31% 25% 8% 2	527
	21st to end	Day	25% 15% 33% 17% 9% 1	573
June	1st to 10th	Day	23% 11% 34% 22% 8% 2	530
	11th to 20th	Day	21% 13% 31% 22% 10% 2	530
	21st to end	Day	25% 11% 29% 23% 10% 2	530
July	1st to 10th	Day	17% 10% 31% 27% 13% 2	525
	11th to 20th	Day	16% 8% 32% 31% 11% 2	524
	21st to end	Day	16% 7% 30% 28% 15% 3	576
August	1st to 10th	Day	17% 6% 26% 31% 17% 3	526
	11th to 20th	Day	18% 4 23% 32% 17% 6%	519
	21st to end	Day	17% 11% 26% 21% 19% 6%	583
September	1st to 10th	Day	18% 9% 34% 22% 13% 5%	530
	11th to 20th	Day	16% 9% 24% 27% 17% 8%	530
	21st to end	Day	23% 11% 25% 23% 12% 6%	530
October	1st to 10th	Day	23% 12% 28% 23% 12% 3	530
	11th to 20th	Day	26% 12% 30% 21% 10% 1	472
	21st to end	Day	33% 9% 31% 20% 7%	462
November	1st to 10th	Day	29% 14% 28% 22% 6% 1	425
	11th to 20th	Day	27% 13% 32% 22% 7% 1	357
	21st to end	Day	30% 20% 30% 14% 5% 1	220
December	1st to 10th	Day	31% 13% 30% 19% 7% 1	220
	11th to 20th	Day	28% 16% 36% 15% 3 1	220
	21st to end	Day	32% 14% 33% 15% 5% 2	242
January	1st to 10th	Night	29% 9% 32% 26% 4	840
	11th to 20th	Night	30% 10% 30% 22% 7%	840
	21st to end	Night	17% 8% 34% 34% 7% 1	924
February	1st to 10th	Night	19% 10% 36% 28% 7%	840
	11th to 20th	Night	23% 12% 37% 22% 5% 1	823
	21st to end	Night	24% 9% 32% 28% 7%	692
March	1st to 10th	Night	25% 11% 32% 28% 4	840
	11th to 20th	Night	25% 13% 33% 24% 5% 1	829
	21st to end	Night	24% 12% 32% 24% 7% 1	880
April	1st to 10th	Night	30% 12% 27% 25% 7%	800
	11th to 20th	Night	27% 11% 30% 26% 5%	761
	21st to end	Night	30% 13% 30% 23% 5%	600
May	1st to 10th	Night	30% 10% 27% 27% 6%	479
	11th to 20th	Night	23% 8% 30% 30% 9%	394
	21st to end	Night	23% 5% 34% 28% 10%	433
June	1st to 10th	Night	24% 4 29% 35% 9% 1	400
	11th to 20th	Night	22% 6% 23% 39% 10% 1	400
	21st to end	Night	22% 6% 23% 37% 13%	400
July	1st to 10th	Night	15% 4 26% 38% 16% 1	390
	11th to 20th	Night	15% 2 24% 43% 15% 1	388
	21st to end	Night	17% 4 21% 42% 15% 1	438
August	1st to 10th	Night	14% 3 16% 48% 19% 1	398
	11th to 20th	Night	17% 4 20% 36% 21% 2	521
	21st to end	Night	20% 5% 22% 34% 18% 1	875
September	1st to 10th	Night	17% 4 27% 36% 14% 1	800
	11th to 20th	Night	17% 5% 23% 32% 21% 1	800
	21st to end	Night	23% 5% 26% 29% 15% 2	800
October	1st to 10th	Night	21% 9% 29% 32% 10% 1	800
	11th to 20th	Night	25% 9% 28% 29% 9% 1	800
	21st to end	Night	31% 8% 31% 25% 6%	880
November	1st to 10th	Night	27% 9% 30% 27% 6% 1	820
	11th to 20th	Night	26% 11% 29% 23% 11% 1	840
	21st to end	Night	32% 12% 25% 25% 6% 1	840
December	1st to 10th	Night	29% 9% 29% 26% 8%	901
	11th to 20th	Night	30% 9% 32% 22% 6% 1	895
	21st to end	Night	32% 11% 28% 23% 5% 1	924

Page generated at 2026-03-15 02:23:57. Version ac07

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