Saint-Lin-Laurentides
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Saint-Lin-Laurentides 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% 3 6% 6% 3 5% 5% 5% 6% 34%	74783
	Night	18% 9% 4 7% 6% 3 4 4 5% 6% 34%	75015
Transparency	Day	49% 8% 13% 19% 10% 1	74488
	Night	50% 7% 12% 19% 10% 1	74844
Seeing	Day	20% 13% 30% 24% 10% 2	13439
	Night	22% 9% 32% 28% 9% 1	22530

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% 16% 5% 11% 8% 3 4 5% 5% 5% 25%	1517
	11th to 20th	Day	17% 15% 6% 8% 5% 3 4 4 4 4 30%	1480
	21st to end	Day	11% 13% 4 9% 7% 3 6% 5% 6% 5% 31%	1584
February	1st to 10th	Day	13% 17% 4 8% 7% 4 5% 5% 4 6% 27%	1571
	11th to 20th	Day	13% 13% 5% 9% 7% 4 6% 5% 5% 4 29%	1658
	21st to end	Day	17% 15% 5% 10% 8% 3 4 4 3 5% 28%	1480
March	1st to 10th	Day	15% 11% 5% 8% 8% 5% 5% 4 5% 6% 29%	1797
	11th to 20th	Day	16% 10% 4 7% 6% 4 4 4 4 6% 34%	1864
	21st to end	Day	18% 9% 3 7% 6% 4 4 3 4 6% 36%	2372
April	1st to 10th	Day	21% 9% 4 7% 5% 4 5% 4 4 4 32%	2160
	11th to 20th	Day	21% 7% 2 5% 5% 3 5% 4 4 6% 37%	2134
	21st to end	Day	22% 9% 4 7% 6% 3 5% 4 4 5% 33%	2309
May	1st to 10th	Day	20% 7% 3 6% 6% 4 4 5% 5% 6% 35%	2496
	11th to 20th	Day	20% 6% 3 6% 6% 3 4 4 5% 7% 36%	2478
	21st to end	Day	18% 6% 3 6% 5% 3 5% 5% 5% 7% 36%	2725
June	1st to 10th	Day	21% 6% 3 6% 6% 4 5% 5% 6% 8% 30%	2520
	11th to 20th	Day	15% 7% 2 5% 5% 3 6% 6% 6% 8% 37%	2520
	21st to end	Day	19% 7% 3 7% 7% 4 6% 5% 6% 6% 30%	2520
July	1st to 10th	Day	12% 4 2 5% 5% 4 7% 6% 6% 8% 40%	2520
	11th to 20th	Day	12% 6% 3 5% 5% 4 7% 7% 8% 9% 36%	2520
	21st to end	Day	12% 5% 3 5% 6% 4 5% 7% 8% 9% 36%	2744
August	1st to 10th	Day	12% 5% 3 6% 6% 4 6% 7% 6% 8% 36%	2506
	11th to 20th	Day	10% 5% 2 6% 7% 4 5% 6% 7% 8% 39%	2302
	21st to end	Day	13% 6% 2 4 5% 3 4 4 7% 8% 44%	2376
September	1st to 10th	Day	13% 4 3 5% 5% 3 5% 5% 6% 8% 43%	2160
	11th to 20th	Day	14% 5% 2 4 4 3 4 4 5% 7% 49%	2087
	21st to end	Day	17% 6% 2 5% 6% 3 4 3 5% 6% 44%	1980
October	1st to 10th	Day	20% 7% 3 5% 5% 4 4 4 6% 7% 36%	1854
	11th to 20th	Day	19% 8% 4 6% 7% 4 5% 6% 4 6% 29%	1758
	21st to end	Day	24% 9% 5% 5% 5% 4 4 4 5% 5% 31%	1782
November	1st to 10th	Day	15% 8% 4 6% 5% 3 5% 5% 5% 7% 36%	1671
	11th to 20th	Day	18% 9% 5% 7% 5% 3 5% 5% 5% 6% 32%	1620
	21st to end	Day	20% 11% 3 7% 6% 4 5% 5% 5% 8% 27%	1520
December	1st to 10th	Day	23% 13% 5% 9% 6% 3 5% 4 4 4 23%	1520
	11th to 20th	Day	21% 15% 4 7% 4 3 4 4 4 5% 28%	1906
	21st to end	Day	27% 16% 5% 9% 5% 3 3 4 3 3 23%	2772
January	1st to 10th	Night	15% 16% 6% 8% 8% 3 4 4 6% 5% 23%	2649
	11th to 20th	Night	15% 15% 5% 9% 6% 3 5% 4 5% 5% 27%	2602
	21st to end	Night	10% 11% 6% 8% 8% 3 5% 5% 5% 6% 33%	2772
February	1st to 10th	Night	13% 13% 6% 10% 8% 4 5% 5% 6% 5% 26%	2385
	11th to 20th	Night	14% 9% 5% 9% 7% 4 5% 5% 5% 5% 33%	2187
	21st to end	Night	16% 12% 4 8% 6% 3 5% 4 4 6% 32%	1776
March	1st to 10th	Night	17% 12% 5% 7% 6% 3 5% 5% 4 5% 31%	2150
	11th to 20th	Night	16% 13% 4 7% 6% 3 4 5% 4 5% 33%	2092
	21st to end	Night	17% 8% 4 6% 5% 4 4 5% 4 4 40%	1983
April	1st to 10th	Night	23% 8% 4 6% 5% 2 4 5% 4 7% 31%	1800
	11th to 20th	Night	21% 7% 3 5% 5% 2 5% 4 5% 6% 38%	1775
	21st to end	Night	21% 10% 3 5% 4 2 4 4 4 5% 36%	1650
May	1st to 10th	Night	22% 8% 3 6% 5% 3 4 4 3 6% 36%	1479
	11th to 20th	Night	20% 6% 3 5% 5% 3 4 5% 5% 6% 39%	1415
	21st to end	Night	17% 6% 3 6% 6% 3 4 4 5% 7% 40%	1550
June	1st to 10th	Night	21% 6% 3 5% 6% 3 4 4 6% 8% 34%	1440
	11th to 20th	Night	17% 7% 3 6% 4 3 4 5% 7% 7% 38%	1440
	21st to end	Night	19% 5% 3 5% 5% 4 5% 5% 5% 8% 36%	1440
July	1st to 10th	Night	11% 4 3 5% 5% 3 5% 6% 6% 8% 44%	1440
	11th to 20th	Night	10% 6% 2 5% 6% 2 6% 6% 7% 8% 41%	1440
	21st to end	Night	11% 5% 3 6% 4 3 5% 5% 6% 9% 43%	1574
August	1st to 10th	Night	12% 4 3 6% 6% 2 5% 6% 6% 9% 43%	1432
	11th to 20th	Night	13% 4 3 5% 5% 3 6% 4 6% 7% 44%	1578
	21st to end	Night	14% 5% 2 5% 4 3 4 4 6% 8% 44%	1980
September	1st to 10th	Night	11% 4 3 5% 6% 4 4 5% 5% 7% 46%	1800
	11th to 20th	Night	14% 5% 2 4 4 2 3 4 5% 7% 50%	1872
	21st to end	Night	17% 5% 2 4 4 2 4 4 4 7% 47%	1980
October	1st to 10th	Night	18% 6% 2 6% 5% 4 4 4 4 4 42%	2103
	11th to 20th	Night	20% 8% 3 6% 5% 3 4 4 5% 6% 36%	2201
	21st to end	Night	22% 9% 3 6% 6% 4 4 4 4 6% 32%	2574
November	1st to 10th	Night	17% 9% 4 6% 6% 3 4 5% 5% 6% 34%	2407
	11th to 20th	Night	19% 9% 3 7% 6% 3 4 5% 5% 6% 35%	2557
	21st to end	Night	21% 12% 4 7% 5% 4 4 3 4 5% 31%	2660
December	1st to 10th	Night	20% 12% 6% 9% 6% 3 5% 5% 5% 6% 23%	2660
	11th to 20th	Night	23% 13% 5% 7% 5% 3 4 4 4 5% 29%	3288
	21st to end	Night	27% 16% 5% 8% 5% 2 3 3 3 4 23%	4884

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	61% 7% 11% 14% 6%	1518
	11th to 20th	Day	59% 5% 11% 13% 11% 1	1480
	21st to end	Day	52% 8% 11% 17% 11% 1	1584
February	1st to 10th	Day	58% 6% 9% 17% 7% 2	1571
	11th to 20th	Day	57% 7% 11% 14% 10% 1	1667
	21st to end	Day	59% 4 10% 15% 9% 2	1480
March	1st to 10th	Day	55% 7% 10% 16% 11% 2	1800
	11th to 20th	Day	51% 6% 13% 15% 13% 3	1864
	21st to end	Day	50% 6% 11% 17% 13% 4	2372
April	1st to 10th	Day	55% 5% 9% 17% 11% 2	2160
	11th to 20th	Day	47% 6% 9% 22% 13% 2	2134
	21st to end	Day	53% 7% 8% 16% 12% 3	2309
May	1st to 10th	Day	50% 6% 9% 19% 13% 2	2496
	11th to 20th	Day	47% 6% 12% 17% 15% 3	2482
	21st to end	Day	45% 9% 12% 18% 14% 2	2725
June	1st to 10th	Day	50% 8% 12% 17% 11% 2	2520
	11th to 20th	Day	43% 9% 13% 20% 12% 3	2520
	21st to end	Day	53% 9% 12% 16% 9% 1	2520
July	1st to 10th	Day	38% 10% 15% 24% 11% 1	2450
	11th to 20th	Day	38% 12% 17% 23% 10%	2445
	21st to end	Day	40% 11% 18% 23% 9%	2591
August	1st to 10th	Day	42% 11% 18% 21% 8%	2492
	11th to 20th	Day	38% 12% 20% 21% 10%	2302
	21st to end	Day	36% 9% 18% 23% 13% 1	2376
September	1st to 10th	Day	36% 10% 15% 25% 13%	2160
	11th to 20th	Day	34% 8% 14% 30% 13% 1	2087
	21st to end	Day	42% 7% 15% 25% 11%	1980
October	1st to 10th	Day	47% 7% 13% 20% 12%	1854
	11th to 20th	Day	53% 9% 14% 19% 6%	1758
	21st to end	Day	56% 6% 13% 16% 8% 1	1782
November	1st to 10th	Day	46% 8% 15% 20% 10% 1	1671
	11th to 20th	Day	51% 7% 15% 16% 10% 1	1620
	21st to end	Day	55% 8% 16% 14% 6% 1	1520
December	1st to 10th	Day	64% 6% 11% 13% 5%	1520
	11th to 20th	Day	58% 7% 11% 17% 7%	1906
	21st to end	Day	65% 7% 12% 10% 6%	2772
January	1st to 10th	Night	61% 7% 11% 15% 5%	2649
	11th to 20th	Night	60% 8% 11% 12% 8% 2	2602
	21st to end	Night	51% 7% 13% 16% 12% 2	2772
February	1st to 10th	Night	59% 7% 10% 16% 8% 1	2385
	11th to 20th	Night	52% 7% 12% 19% 9% 1	2189
	21st to end	Night	54% 5% 9% 17% 13% 1	1776
March	1st to 10th	Night	54% 7% 9% 17% 11% 2	2160
	11th to 20th	Night	53% 6% 10% 16% 13% 3	2093
	21st to end	Night	49% 6% 8% 19% 14% 4	1983
April	1st to 10th	Night	52% 6% 9% 18% 13% 2	1800
	11th to 20th	Night	47% 6% 9% 21% 15% 2	1775
	21st to end	Night	49% 6% 9% 19% 13% 4	1650
May	1st to 10th	Night	49% 5% 9% 18% 14% 5%	1479
	11th to 20th	Night	44% 8% 11% 16% 17% 4	1416
	21st to end	Night	44% 7% 11% 20% 16% 2	1551
June	1st to 10th	Night	48% 7% 12% 20% 12% 1	1440
	11th to 20th	Night	43% 8% 11% 20% 13% 3	1440
	21st to end	Night	46% 9% 11% 19% 14%	1440
July	1st to 10th	Night	34% 10% 15% 26% 14% 1	1400
	11th to 20th	Night	37% 9% 16% 27% 11%	1392
	21st to end	Night	36% 9% 20% 23% 11%	1486
August	1st to 10th	Night	38% 10% 17% 25% 10%	1422
	11th to 20th	Night	37% 9% 17% 24% 12%	1578
	21st to end	Night	36% 9% 16% 26% 12%	1980
September	1st to 10th	Night	35% 10% 16% 25% 14% 1	1800
	11th to 20th	Night	35% 6% 15% 32% 11% 1	1872
	21st to end	Night	38% 7% 12% 29% 13%	1980
October	1st to 10th	Night	45% 7% 10% 23% 14% 1	2103
	11th to 20th	Night	48% 8% 13% 23% 8%	2201
	21st to end	Night	53% 7% 13% 17% 9% 1	2574
November	1st to 10th	Night	49% 8% 14% 20% 8% 1	2407
	11th to 20th	Night	50% 7% 14% 19% 10% 1	2557
	21st to end	Night	57% 7% 11% 18% 7% 1	2660
December	1st to 10th	Night	61% 8% 12% 15% 4	2660
	11th to 20th	Night	58% 6% 11% 18% 7% 1	3288
	21st to end	Night	64% 6% 9% 15% 5%	4884

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	19% 18% 32% 25% 6%	180
	11th to 20th	Day	24% 15% 38% 18% 4 1	170
	21st to end	Day	18% 15% 36% 25% 5% 1	176
February	1st to 10th	Day	29% 26% 34% 10%	219
	11th to 20th	Day	20% 15% 42% 19% 2	325
	21st to end	Day	29% 14% 34% 21% 3	346
March	1st to 10th	Day	24% 14% 34% 22% 6%	420
	11th to 20th	Day	21% 20% 32% 23% 4 1	420
	21st to end	Day	26% 16% 30% 18% 9% 1	462
April	1st to 10th	Day	25% 17% 30% 21% 7% 1	420
	11th to 20th	Day	27% 19% 25% 19% 9% 2	412
	21st to end	Day	27% 15% 32% 18% 6% 1	420
May	1st to 10th	Day	23% 14% 35% 20% 6% 1	423
	11th to 20th	Day	20% 14% 33% 22% 9% 2	447
	21st to end	Day	18% 15% 36% 22% 7% 2	485
June	1st to 10th	Day	23% 10% 33% 23% 9% 1	450
	11th to 20th	Day	16% 14% 28% 28% 11% 2	450
	21st to end	Day	21% 12% 26% 28% 11% 2	450
July	1st to 10th	Day	13% 7% 29% 32% 15% 4	445
	11th to 20th	Day	13% 7% 30% 33% 14% 2	444
	21st to end	Day	13% 7% 29% 33% 16% 3	488
August	1st to 10th	Day	14% 8% 23% 34% 18% 3	446
	11th to 20th	Day	11% 5% 25% 34% 16% 9%	439
	21st to end	Day	15% 9% 27% 25% 16% 8%	495
September	1st to 10th	Day	14% 6% 30% 29% 14% 7%	450
	11th to 20th	Day	13% 10% 25% 28% 16% 8%	450
	21st to end	Day	18% 10% 28% 23% 15% 6%	450
October	1st to 10th	Day	24% 12% 26% 23% 11% 3	450
	11th to 20th	Day	19% 18% 31% 20% 11% 1	428
	21st to end	Day	28% 15% 30% 21% 6%	396
November	1st to 10th	Day	23% 15% 32% 22% 8% 1	365
	11th to 20th	Day	23% 17% 35% 17% 8%	280
	21st to end	Day	26% 16% 33% 16% 8% 1	180
December	1st to 10th	Day	27% 18% 23% 23% 8% 1	180
	11th to 20th	Day	22% 18% 39% 18% 1 1	180
	21st to end	Day	32% 17% 30% 15% 6% 1	198
January	1st to 10th	Night	24% 13% 33% 25% 4	760
	11th to 20th	Night	23% 12% 36% 24% 5%	744
	21st to end	Night	16% 10% 38% 28% 7% 1	792
February	1st to 10th	Night	20% 11% 40% 24% 4 1	720
	11th to 20th	Night	19% 12% 41% 22% 5%	703
	21st to end	Night	21% 10% 38% 27% 4	592
March	1st to 10th	Night	24% 14% 33% 26% 4	720
	11th to 20th	Night	23% 13% 33% 23% 7%	720
	21st to end	Night	21% 8% 38% 26% 6%	792
April	1st to 10th	Night	28% 11% 30% 27% 5%	720
	11th to 20th	Night	25% 12% 32% 26% 5% 1	711
	21st to end	Night	27% 11% 32% 23% 7%	570
May	1st to 10th	Night	23% 10% 33% 28% 7% 1	399
	11th to 20th	Night	22% 9% 32% 30% 7%	354
	21st to end	Night	20% 6% 38% 27% 8%	389
June	1st to 10th	Night	24% 5% 33% 29% 9%	360
	11th to 20th	Night	19% 7% 30% 31% 13%	360
	21st to end	Night	20% 6% 28% 32% 14%	360
July	1st to 10th	Night	10% 7% 32% 36% 15% 1	350
	11th to 20th	Night	12% 4 26% 44% 14%	348
	21st to end	Night	12% 3 26% 43% 14% 1	394
August	1st to 10th	Night	14% 4 16% 46% 19%	358
	11th to 20th	Night	13% 4 24% 35% 22% 2	514
	21st to end	Night	15% 6% 25% 34% 19% 2	792
September	1st to 10th	Night	14% 4 27% 39% 15% 1	720
	11th to 20th	Night	15% 6% 24% 34% 20% 2	720
	21st to end	Night	19% 5% 29% 30% 15% 2	720
October	1st to 10th	Night	21% 6% 31% 31% 10% 1	720
	11th to 20th	Night	23% 8% 30% 29% 9% 1	720
	21st to end	Night	28% 9% 33% 24% 6%	792
November	1st to 10th	Night	21% 12% 33% 25% 8% 1	740
	11th to 20th	Night	24% 11% 34% 21% 9% 1	760
	21st to end	Night	27% 12% 33% 20% 7% 1	760
December	1st to 10th	Night	28% 11% 32% 22% 6%	760
	11th to 20th	Night	27% 13% 33% 22% 4 1	760
	21st to end	Night	31% 12% 32% 19% 5%	836

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