La Malbaie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the La Malbaie clear sky chart from 2005-11-06 to 2024-09-29.

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	15% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	101260
	Night	15% 11% 4 9% 5% 5% 5% 4 5% 6% 32%	97004
Transparency	Day	25% 50% 9% 11% 5% 1	101010
	Night	27% 51% 7% 10% 5%	96876
Seeing	Day	22% 17% 30% 21% 8% 2	15456
	Night	21% 12% 27% 30% 10% 1	23613

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	12% 15% 4 10% 7% 5% 5% 4 5% 6% 27%	2358
	11th to 20th	Day	10% 11% 5% 10% 8% 5% 6% 5% 7% 7% 27%	2520
	21st to end	Day	8% 8% 4 10% 6% 7% 6% 5% 7% 7% 32%	2772
February	1st to 10th	Day	7% 12% 4 8% 9% 9% 6% 6% 6% 5% 27%	1550
	11th to 20th	Day	10% 13% 5% 12% 8% 5% 5% 4 6% 5% 27%	1762
	21st to end	Day	12% 9% 4 8% 8% 6% 6% 5% 7% 6% 31%	1570
March	1st to 10th	Day	16% 10% 4 9% 5% 4 5% 4 6% 6% 31%	3116
	11th to 20th	Day	15% 15% 5% 10% 6% 4 5% 4 5% 6% 25%	3384
	21st to end	Day	13% 15% 4 8% 5% 4 3 3 5% 6% 35%	3962
April	1st to 10th	Day	18% 13% 4 8% 5% 4 5% 4 5% 6% 28%	2280
	11th to 20th	Day	16% 7% 3 8% 4 6% 5% 3 5% 6% 38%	2404
	21st to end	Day	20% 10% 2 6% 4 4 5% 3 5% 6% 33%	2470
May	1st to 10th	Day	14% 8% 3 8% 6% 5% 5% 4 6% 6% 35%	4157
	11th to 20th	Day	18% 7% 2 6% 4 4 5% 4 5% 8% 36%	4398
	21st to end	Day	16% 7% 3 7% 5% 5% 5% 5% 6% 8% 33%	5175
June	1st to 10th	Day	18% 8% 3 6% 6% 5% 6% 4 6% 8% 31%	2850
	11th to 20th	Day	16% 6% 3 6% 5% 5% 5% 5% 5% 7% 37%	2850
	21st to end	Day	19% 9% 3 6% 5% 5% 5% 5% 6% 8% 29%	2850
July	1st to 10th	Day	12% 5% 3 7% 5% 5% 6% 5% 8% 10% 34%	4760
	11th to 20th	Day	11% 6% 3 7% 5% 5% 6% 5% 7% 10% 35%	4504
	21st to end	Day	11% 6% 2 6% 4 5% 6% 5% 6% 9% 41%	4814
August	1st to 10th	Day	11% 5% 3 7% 6% 6% 7% 5% 8% 9% 33%	4346
	11th to 20th	Day	14% 6% 3 7% 6% 5% 5% 5% 7% 9% 32%	4045
	21st to end	Day	16% 5% 2 5% 4 4 5% 4 5% 7% 43%	4478
September	1st to 10th	Day	12% 7% 2 6% 5% 4 5% 3 6% 7% 42%	2265
	11th to 20th	Day	13% 5% 2 5% 4 4 4 3 6% 7% 48%	2090
	21st to end	Day	16% 6% 2 6% 3 4 4 4 6% 9% 40%	2070
October	1st to 10th	Day	16% 6% 2 7% 4 5% 4 4 6% 7% 38%	1957
	11th to 20th	Day	20% 8% 3 7% 5% 5% 5% 4 6% 7% 30%	1663
	21st to end	Day	23% 11% 4 8% 4 5% 4 3 5% 5% 27%	1782
November	1st to 10th	Day	15% 11% 2 9% 7% 5% 4 5% 5% 6% 31%	1671
	11th to 20th	Day	16% 9% 4 9% 5% 6% 6% 4 5% 7% 26%	1604
	21st to end	Day	17% 14% 4 10% 6% 5% 4 3 5% 5% 27%	1354
December	1st to 10th	Day	17% 16% 5% 10% 6% 5% 5% 2 4 6% 24%	1330
	11th to 20th	Day	19% 12% 5% 10% 6% 4 4 2 4 4 30%	1668
	21st to end	Day	20% 13% 3 9% 4 4 3 3 4 3 34%	2431
January	1st to 10th	Night	11% 16% 6% 12% 7% 5% 5% 4 4 5% 23%	4588
	11th to 20th	Night	10% 14% 5% 11% 7% 6% 5% 4 6% 7% 26%	4440
	21st to end	Night	6% 11% 5% 12% 8% 7% 6% 5% 6% 7% 28%	4884
February	1st to 10th	Night	7% 14% 4 10% 6% 5% 5% 4 7% 7% 31%	2629
	11th to 20th	Night	9% 14% 5% 13% 8% 6% 4 4 5% 5% 27%	2300
	21st to end	Night	12% 12% 4 10% 6% 4 5% 4 4 8% 32%	1884
March	1st to 10th	Night	19% 12% 4 10% 5% 4 6% 3 5% 6% 28%	3724
	11th to 20th	Night	13% 17% 5% 12% 7% 5% 5% 4 5% 4 22%	3575
	21st to end	Night	18% 15% 4 8% 4 4 4 4 4 5% 31%	3668
April	1st to 10th	Night	20% 12% 5% 9% 4 4 4 3 5% 4 31%	1900
	11th to 20th	Night	18% 9% 3 8% 6% 5% 4 3 5% 6% 34%	1725
	21st to end	Night	23% 10% 3 6% 3 3 4 4 5% 5% 34%	1710
May	1st to 10th	Night	18% 8% 2 7% 5% 4 5% 4 6% 6% 35%	2812
	11th to 20th	Night	18% 10% 3 7% 5% 5% 4 3 6% 7% 32%	2495
	21st to end	Night	17% 5% 3 6% 4 4 5% 5% 7% 9% 34%	2410
June	1st to 10th	Night	18% 8% 3 8% 5% 4 5% 4 6% 7% 32%	1330
	11th to 20th	Night	15% 5% 2 7% 5% 4 4 5% 6% 8% 40%	1330
	21st to end	Night	20% 8% 3 7% 5% 4 5% 5% 5% 7% 31%	1330
July	1st to 10th	Night	12% 7% 3 7% 5% 5% 4 5% 8% 8% 37%	2210
	11th to 20th	Night	13% 6% 3 7% 5% 5% 5% 4 7% 8% 37%	2454
	21st to end	Night	10% 5% 2 6% 4 5% 5% 3 6% 10% 44%	2739
August	1st to 10th	Night	15% 6% 3 8% 5% 5% 6% 4 6% 8% 35%	2538
	11th to 20th	Night	13% 6% 3 10% 7% 6% 7% 5% 8% 8% 28%	2782
	21st to end	Night	16% 7% 3 7% 4 4 4 3 5% 7% 42%	3176
September	1st to 10th	Night	14% 5% 2 6% 4 4 4 3 6% 8% 42%	1914
	11th to 20th	Night	16% 7% 2 6% 3 5% 4 3 4 6% 43%	2090
	21st to end	Night	16% 6% 2 6% 5% 4 3 3 4 6% 44%	2078
October	1st to 10th	Night	16% 8% 3 7% 4 3 4 3 4 5% 42%	2002
	11th to 20th	Night	23% 8% 2 6% 4 4 4 4 6% 6% 33%	2294
	21st to end	Night	21% 9% 3 7% 5% 4 4 3 5% 7% 31%	2574
November	1st to 10th	Night	16% 10% 3 7% 5% 5% 4 3 6% 7% 33%	2407
	11th to 20th	Night	18% 10% 4 7% 4 5% 4 4 6% 7% 30%	2574
	21st to end	Night	16% 14% 4 9% 5% 5% 5% 4 5% 5% 28%	2821
December	1st to 10th	Night	17% 15% 6% 10% 5% 5% 4 4 5% 5% 25%	2850
	11th to 20th	Night	20% 11% 4 9% 6% 5% 4 4 5% 6% 26%	3531
	21st to end	Night	18% 16% 4 9% 5% 4 4 3 5% 5% 28%	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	33% 41% 10% 13% 3	2359
	11th to 20th	Day	33% 43% 5% 14% 6%	2520
	21st to end	Day	28% 45% 7% 10% 10%	2772
February	1st to 10th	Day	18% 65% 4 7% 4 1	1550
	11th to 20th	Day	20% 65% 4 6% 4	1770
	21st to end	Day	17% 66% 4 8% 4 2	1570
March	1st to 10th	Day	31% 43% 9% 9% 5% 3	3119
	11th to 20th	Day	37% 44% 9% 7% 3 1	3384
	21st to end	Day	31% 42% 4 11% 8% 4	3962
April	1st to 10th	Day	18% 65% 3 7% 5% 2	2280
	11th to 20th	Day	18% 67% 5% 8% 2 1	2404
	21st to end	Day	20% 66% 3 6% 4 1	2470
May	1st to 10th	Day	29% 44% 10% 10% 7%	4171
	11th to 20th	Day	28% 43% 12% 14% 3	4402
	21st to end	Day	29% 45% 7% 12% 7%	5175
June	1st to 10th	Day	16% 66% 4 9% 4	2850
	11th to 20th	Day	15% 66% 7% 7% 4	2850
	21st to end	Day	17% 64% 5% 9% 3	2850
July	1st to 10th	Day	28% 39% 13% 15% 6%	4685
	11th to 20th	Day	26% 39% 19% 14% 2	4427
	21st to end	Day	24% 39% 13% 18% 6%	4661
August	1st to 10th	Day	26% 42% 15% 13% 4	4332
	11th to 20th	Day	32% 41% 15% 11% 2	4084
	21st to end	Day	26% 39% 15% 11% 9%	4478
September	1st to 10th	Day	15% 61% 10% 11% 4	2265
	11th to 20th	Day	15% 61% 9% 11% 4 1	2090
	21st to end	Day	16% 60% 7% 12% 5%	2070
October	1st to 10th	Day	16% 64% 5% 10% 5%	1957
	11th to 20th	Day	19% 65% 5% 8% 2	1663
	21st to end	Day	25% 62% 6% 5% 2	1782
November	1st to 10th	Day	22% 61% 7% 6% 3	1671
	11th to 20th	Day	23% 62% 5% 8% 3	1604
	21st to end	Day	25% 61% 5% 6% 3	1354
December	1st to 10th	Day	27% 61% 3 7% 3	1330
	11th to 20th	Day	32% 50% 3 10% 5%	1668
	21st to end	Day	33% 38% 8% 13% 4 3	2431
January	1st to 10th	Night	37% 42% 8% 7% 6% 1	4588
	11th to 20th	Night	36% 42% 5% 11% 6%	4440
	21st to end	Night	31% 46% 6% 10% 6% 1	4884
February	1st to 10th	Night	18% 65% 4 8% 5% 1	2629
	11th to 20th	Night	21% 65% 3 8% 4	2303
	21st to end	Night	18% 65% 2 7% 7% 1	1884
March	1st to 10th	Night	35% 45% 6% 8% 5% 1	3734
	11th to 20th	Night	38% 43% 8% 8% 2 1	3576
	21st to end	Night	36% 42% 5% 11% 6% 1	3668
April	1st to 10th	Night	19% 65% 2 7% 7% 1	1900
	11th to 20th	Night	20% 66% 3 7% 4	1725
	21st to end	Night	23% 65% 2 5% 4 1	1710
May	1st to 10th	Night	27% 44% 9% 12% 7%	2818
	11th to 20th	Night	30% 44% 9% 11% 5%	2496
	21st to end	Night	24% 44% 8% 16% 7%	2411
June	1st to 10th	Night	19% 66% 3 10% 2	1330
	11th to 20th	Night	15% 66% 6% 7% 5% 1	1330
	21st to end	Night	19% 64% 5% 8% 4	1330
July	1st to 10th	Night	29% 38% 14% 17% 2	2175
	11th to 20th	Night	26% 38% 17% 17% 2	2409
	21st to end	Night	20% 38% 19% 15% 8%	2651
August	1st to 10th	Night	31% 40% 12% 13% 4	2528
	11th to 20th	Night	34% 43% 13% 6% 4	2809
	21st to end	Night	27% 39% 8% 18% 8%	3176
September	1st to 10th	Night	15% 62% 6% 11% 5%	1914
	11th to 20th	Night	19% 61% 7% 9% 3	2090
	21st to end	Night	14% 61% 5% 13% 6% 1	2078
October	1st to 10th	Night	17% 63% 3 11% 6%	2002
	11th to 20th	Night	18% 65% 6% 8% 2	2294
	21st to end	Night	22% 63% 5% 6% 3	2574
November	1st to 10th	Night	25% 60% 5% 6% 3	2407
	11th to 20th	Night	22% 63% 4 7% 3	2574
	21st to end	Night	26% 61% 4 4 4	2821
December	1st to 10th	Night	25% 61% 3 7% 3	2850
	11th to 20th	Night	33% 51% 4 7% 5% 1	3532
	21st to end	Night	36% 40% 8% 9% 6% 1	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% 14% 36% 22% 6% 1	180
	11th to 20th	Day	27% 12% 37% 17% 7% 1	180
	21st to end	Day	16% 20% 39% 15% 10% 2	198
February	1st to 10th	Day	17% 26% 34% 18% 6%	210
	11th to 20th	Day	16% 21% 38% 20% 5%	414
	21st to end	Day	21% 20% 34% 19% 5% 1	382
March	1st to 10th	Day	25% 19% 28% 21% 7%	460
	11th to 20th	Day	22% 22% 28% 20% 7% 1	460
	21st to end	Day	25% 24% 28% 14% 7% 2	506
April	1st to 10th	Day	27% 23% 27% 17% 4 1	460
	11th to 20th	Day	27% 19% 30% 16% 7% 1	452
	21st to end	Day	28% 17% 36% 14% 4 2	460
May	1st to 10th	Day	26% 19% 30% 17% 6% 2	463
	11th to 20th	Day	22% 22% 27% 22% 5% 1	487
	21st to end	Day	23% 19% 32% 19% 5% 1	724
June	1st to 10th	Day	26% 17% 27% 21% 8% 1	680
	11th to 20th	Day	23% 17% 24% 24% 10% 1	680
	21st to end	Day	24% 11% 30% 24% 9% 2	680
July	1st to 10th	Day	19% 13% 32% 25% 10% 2	670
	11th to 20th	Day	17% 12% 34% 27% 8% 2	520
	21st to end	Day	16% 10% 34% 30% 9% 2	532
August	1st to 10th	Day	17% 14% 28% 26% 13% 3	486
	11th to 20th	Day	16% 13% 29% 27% 12% 3	479
	21st to end	Day	17% 16% 30% 19% 14% 4	539
September	1st to 10th	Day	17% 15% 32% 24% 8% 4	490
	11th to 20th	Day	19% 12% 31% 22% 11% 4	490
	21st to end	Day	21% 14% 29% 19% 12% 5%	483
October	1st to 10th	Day	19% 20% 26% 22% 10% 2	438
	11th to 20th	Day	26% 17% 28% 18% 10% 1	360
	21st to end	Day	35% 14% 28% 17% 6%	396
November	1st to 10th	Day	27% 17% 27% 23% 5% 1	365
	11th to 20th	Day	24% 14% 26% 23% 11% 1	370
	21st to end	Day	30% 21% 32% 15% 1	204
December	1st to 10th	Day	23% 19% 27% 17% 11% 3	180
	11th to 20th	Day	27% 21% 32% 14% 4 2	180
	21st to end	Day	30% 19% 21% 25% 4 1	198
January	1st to 10th	Night	20% 12% 29% 33% 6% 1	805
	11th to 20th	Night	20% 12% 33% 29% 6% 1	760
	21st to end	Night	12% 10% 29% 39% 9% 1	836
February	1st to 10th	Night	14% 13% 35% 29% 9% 1	760
	11th to 20th	Night	17% 14% 35% 27% 7% 1	743
	21st to end	Night	19% 13% 29% 32% 6% 1	628
March	1st to 10th	Night	17% 15% 32% 29% 6% 1	760
	11th to 20th	Night	21% 14% 34% 22% 7% 1	760
	21st to end	Night	21% 18% 27% 27% 6%	836
April	1st to 10th	Night	29% 12% 30% 23% 5% 1	760
	11th to 20th	Night	23% 14% 32% 22% 8%	601
	21st to end	Night	29% 14% 27% 23% 7% 1	570
May	1st to 10th	Night	25% 11% 29% 28% 6% 1	561
	11th to 20th	Night	26% 9% 25% 27% 12% 1	374
	21st to end	Night	25% 14% 28% 23% 9%	411
June	1st to 10th	Night	21% 9% 23% 36% 10% 1	380
	11th to 20th	Night	18% 7% 21% 34% 17% 2	380
	21st to end	Night	23% 8% 23% 33% 12% 1	380
July	1st to 10th	Night	17% 6% 26% 40% 11% 1	370
	11th to 20th	Night	15% 3 23% 44% 13% 1	368
	21st to end	Night	15% 5% 21% 45% 14% 1	416
August	1st to 10th	Night	16% 4 19% 44% 17% 1	397
	11th to 20th	Night	17% 5% 20% 36% 20% 2	562
	21st to end	Night	14% 9% 23% 35% 17% 1	653
September	1st to 10th	Night	17% 8% 24% 35% 14% 1	760
	11th to 20th	Night	22% 8% 21% 31% 16% 3	760
	21st to end	Night	20% 9% 23% 32% 15% 1	756
October	1st to 10th	Night	21% 13% 22% 33% 10% 2	720
	11th to 20th	Night	26% 9% 26% 27% 12% 1	720
	21st to end	Night	25% 13% 27% 26% 9%	792
November	1st to 10th	Night	23% 15% 26% 28% 8% 1	740
	11th to 20th	Night	24% 15% 27% 26% 8% 1	809
	21st to end	Night	23% 16% 25% 29% 7% 1	850
December	1st to 10th	Night	24% 13% 28% 26% 7% 1	850
	11th to 20th	Night	23% 15% 27% 26% 8%	850
	21st to end	Night	24% 14% 28% 24% 8% 1	935

Page generated at 2024-09-26 09:52:24. Version ac07

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