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 2024-12-06.

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 8% 5% 5% 5% 4 6% 7% 34%	101815
	Night	17% 10% 4 8% 5% 4 4 3 5% 6% 34%	97921
Transparency	Day	47% 8% 14% 20% 10% 1	105278
	Night	49% 8% 13% 19% 10% 1	102547
Seeing	Day	20% 13% 30% 24% 10% 2	14620
	Night	21% 10% 32% 28% 9% 1	23608

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% 15% 4 12% 6% 4 4 4 5% 4 25%	2517
	11th to 20th	Day	13% 13% 5% 10% 6% 4 5% 3 5% 6% 29%	2520
	21st to end	Day	12% 16% 6% 11% 6% 5% 5% 4 6% 5% 25%	2772
February	1st to 10th	Day	13% 17% 4 9% 7% 5% 4 4 4 5% 28%	1658
	11th to 20th	Day	12% 13% 5% 10% 6% 5% 6% 4 5% 4 29%	1753
	21st to end	Day	16% 16% 3 11% 6% 3 4 4 4 5% 28%	1570
March	1st to 10th	Day	19% 12% 4 9% 7% 5% 4 3 5% 5% 27%	3116
	11th to 20th	Day	12% 16% 5% 11% 5% 5% 4 3 4 6% 29%	3280
	21st to end	Day	14% 9% 3 8% 5% 5% 4 3 5% 6% 38%	4162
April	1st to 10th	Day	21% 11% 3 8% 5% 4 5% 3 4 4 32%	2280
	11th to 20th	Day	21% 8% 2 6% 5% 4 4 3 5% 5% 36%	2254
	21st to end	Day	21% 9% 3 7% 5% 4 4 4 4 5% 33%	2438
May	1st to 10th	Day	20% 8% 3 8% 5% 5% 4 4 5% 7% 31%	4388
	11th to 20th	Day	18% 8% 3 8% 5% 5% 5% 4 6% 8% 32%	4398
	21st to end	Day	16% 5% 2 7% 5% 5% 5% 4 6% 8% 37%	4837
June	1st to 10th	Day	21% 7% 3 7% 5% 6% 5% 4 6% 7% 30%	2660
	11th to 20th	Day	14% 7% 2 7% 5% 4 6% 5% 6% 8% 36%	2660
	21st to end	Day	20% 8% 3 8% 6% 6% 5% 4 6% 6% 29%	2660
July	1st to 10th	Day	12% 5% 2 7% 5% 5% 6% 5% 7% 9% 36%	4440
	11th to 20th	Day	13% 6% 2 5% 5% 5% 6% 5% 8% 9% 36%	4440
	21st to end	Day	11% 5% 2 5% 4 4 4 4 6% 8% 46%	4814
August	1st to 10th	Day	14% 5% 2 7% 5% 6% 6% 5% 7% 9% 32%	4423
	11th to 20th	Day	14% 6% 3 8% 5% 4 4 4 7% 8% 37%	4026
	21st to end	Day	16% 5% 2 6% 4 5% 4 4 7% 8% 40%	4180
September	1st to 10th	Day	13% 5% 2 6% 4 4 5% 4 6% 8% 43%	2280
	11th to 20th	Day	13% 5% 2 5% 3 3 3 3 5% 7% 50%	2202
	21st to end	Day	17% 6% 2 6% 5% 4 4 3 5% 6% 43%	2090
October	1st to 10th	Day	19% 7% 3 6% 3 5% 3 3 6% 7% 36%	1957
	11th to 20th	Day	18% 8% 4 7% 7% 5% 5% 4 5% 6% 31%	1855
	21st to end	Day	22% 10% 4 6% 4 5% 4 3 5% 5% 32%	1881
November	1st to 10th	Day	14% 9% 3 7% 5% 4 5% 4 5% 7% 36%	1761
	11th to 20th	Day	17% 10% 4 8% 4 4 5% 4 6% 6% 33%	1705
	21st to end	Day	21% 12% 3 7% 6% 5% 4 4 4 8% 26%	1600
December	1st to 10th	Day	22% 16% 5% 9% 5% 4 5% 3 4 4 23%	1560
	11th to 20th	Day	20% 16% 3 8% 4 4 4 3 5% 5% 28%	1906
	21st to end	Day	27% 17% 4 10% 4 4 3 3 3 3 22%	2772
January	1st to 10th	Night	15% 15% 5% 9% 6% 5% 4 4 5% 5% 27%	4429
	11th to 20th	Night	11% 13% 5% 12% 6% 6% 5% 4 5% 6% 28%	4440
	21st to end	Night	13% 15% 5% 11% 6% 5% 4 4 5% 5% 26%	4884
February	1st to 10th	Night	13% 14% 5% 11% 7% 5% 4 4 6% 5% 26%	2518
	11th to 20th	Night	13% 10% 4 10% 6% 4 5% 4 5% 5% 32%	2312
	21st to end	Night	15% 13% 4 9% 5% 4 5% 3 4 6% 32%	1884
March	1st to 10th	Night	20% 12% 4 6% 5% 4 4 3 4 4 33%	3724
	11th to 20th	Night	15% 18% 4 10% 6% 4 4 3 4 4 29%	3676
	21st to end	Night	13% 9% 4 9% 5% 5% 4 4 4 4 39%	3469
April	1st to 10th	Night	23% 10% 3 7% 5% 4 4 3 4 7% 31%	1900
	11th to 20th	Night	21% 8% 3 6% 4 3 4 3 5% 6% 37%	1875
	21st to end	Night	21% 10% 3 6% 3 3 4 3 5% 5% 37%	1741
May	1st to 10th	Night	21% 9% 2 8% 5% 5% 4 3 4 6% 32%	2581
	11th to 20th	Night	21% 7% 2 6% 4 4 4 4 5% 7% 35%	2495
	21st to end	Night	16% 7% 3 7% 5% 4 4 4 5% 8% 36%	2738
June	1st to 10th	Night	20% 7% 3 6% 6% 5% 3 4 6% 8% 34%	1520
	11th to 20th	Night	17% 7% 2 6% 4 4 4 4 7% 7% 38%	1520
	21st to end	Night	20% 6% 3 6% 4 4 5% 4 6% 7% 35%	1520
July	1st to 10th	Night	12% 6% 3 8% 5% 5% 6% 5% 7% 7% 35%	2520
	11th to 20th	Night	13% 6% 2 5% 4 4 5% 4 6% 7% 43%	2520
	21st to end	Night	10% 6% 2 6% 4 4 5% 4 6% 7% 46%	2739
August	1st to 10th	Night	14% 6% 3 8% 5% 4 5% 5% 5% 7% 39%	2506
	11th to 20th	Night	15% 7% 3 7% 4 4 5% 3 6% 6% 40%	2768
	21st to end	Night	17% 6% 3 7% 4 4 4 3 6% 7% 40%	3476
September	1st to 10th	Night	11% 5% 2 6% 4 5% 5% 3 5% 7% 47%	1900
	11th to 20th	Night	13% 5% 2 5% 3 3 3 3 5% 7% 51%	1977
	21st to end	Night	17% 6% 1 6% 4 3 4 3 4 6% 47%	2090
October	1st to 10th	Night	18% 7% 3 7% 4 5% 4 3 4 4 42%	2220
	11th to 20th	Night	19% 8% 3 7% 4 4 4 3 5% 6% 37%	2324
	21st to end	Night	21% 9% 3 7% 5% 5% 4 3 4 6% 33%	2717
November	1st to 10th	Night	17% 9% 3 7% 5% 5% 4 4 5% 6% 34%	2537
	11th to 20th	Night	18% 9% 3 8% 5% 4 5% 4 5% 5% 35%	2692
	21st to end	Night	21% 13% 3 8% 5% 4 4 3 4 5% 30%	2800
December	1st to 10th	Night	20% 13% 6% 10% 6% 4 5% 4 5% 5% 23%	2737
	11th to 20th	Night	23% 14% 4 8% 5% 3 4 3 4 4 28%	3288
	21st to end	Night	26% 17% 4 9% 4 3 3 2 4 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	57% 10% 14% 14% 5% 1	2518
	11th to 20th	Day	53% 8% 15% 16% 7%	2520
	21st to end	Day	58% 9% 12% 14% 7% 1	2772
February	1st to 10th	Day	57% 7% 10% 18% 7% 2	1658
	11th to 20th	Day	56% 8% 11% 14% 10% 1	1762
	21st to end	Day	58% 5% 11% 15% 9% 2	1570
March	1st to 10th	Day	58% 8% 9% 15% 8% 1	3119
	11th to 20th	Day	53% 9% 13% 12% 10% 3	3280
	21st to end	Day	44% 7% 11% 19% 17% 2	4162
April	1st to 10th	Day	55% 5% 9% 18% 11% 2	2280
	11th to 20th	Day	48% 7% 9% 22% 13% 2	2254
	21st to end	Day	52% 7% 8% 17% 12% 3	2438
May	1st to 10th	Day	49% 9% 11% 20% 9% 1	4402
	11th to 20th	Day	46% 10% 18% 15% 9% 2	4402
	21st to end	Day	41% 10% 13% 21% 14% 1	4837
June	1st to 10th	Day	50% 8% 12% 17% 11% 2	2660
	11th to 20th	Day	42% 9% 14% 20% 12% 3	2660
	21st to end	Day	53% 9% 12% 16% 9% 1	2660
July	1st to 10th	Day	41% 9% 16% 23% 10%	4370
	11th to 20th	Day	38% 11% 18% 25% 7%	4365
	21st to end	Day	35% 8% 16% 31% 10%	4661
August	1st to 10th	Day	44% 10% 18% 20% 8%	4409
	11th to 20th	Day	41% 10% 20% 23% 6%	4068
	21st to end	Day	39% 8% 17% 20% 14% 1	4180
September	1st to 10th	Day	35% 10% 16% 26% 12%	2280
	11th to 20th	Day	33% 8% 15% 30% 13% 1	2202
	21st to end	Day	42% 7% 14% 25% 11%	2090
October	1st to 10th	Day	44% 8% 15% 24% 9%	3256
	11th to 20th	Day	42% 7% 18% 26% 7%	3058
	21st to end	Day	41% 6% 22% 21% 10% 1	3081
November	1st to 10th	Day	46% 8% 15% 20% 9% 1	1761
	11th to 20th	Day	50% 7% 15% 17% 11% 1	1705
	21st to end	Day	56% 8% 15% 14% 5% 1	1600
December	1st to 10th	Day	65% 6% 11% 13% 5%	1560
	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	57% 9% 16% 13% 5%	4429
	11th to 20th	Night	53% 11% 15% 15% 5% 1	4440
	21st to end	Night	57% 10% 14% 11% 7% 1	4884
February	1st to 10th	Night	58% 7% 11% 16% 7% 1	2518
	11th to 20th	Night	52% 7% 12% 19% 10% 1	2314
	21st to end	Night	54% 6% 10% 17% 13% 2	1884
March	1st to 10th	Night	52% 8% 11% 16% 9% 4	3734
	11th to 20th	Night	55% 9% 10% 13% 12% 2	3677
	21st to end	Night	46% 7% 8% 21% 14% 3	3469
April	1st to 10th	Night	52% 6% 9% 18% 14% 1	1900
	11th to 20th	Night	48% 6% 9% 20% 14% 2	1875
	21st to end	Night	48% 6% 9% 19% 14% 4	1741
May	1st to 10th	Night	50% 9% 12% 18% 8% 3	2587
	11th to 20th	Night	45% 10% 16% 16% 11% 2	2496
	21st to end	Night	45% 8% 11% 19% 16% 1	2739
June	1st to 10th	Night	48% 7% 12% 19% 13% 1	1520
	11th to 20th	Night	43% 8% 12% 20% 14% 3	1520
	21st to end	Night	48% 9% 11% 18% 14% 1	1520
July	1st to 10th	Night	43% 9% 17% 19% 11% 1	2480
	11th to 20th	Night	37% 9% 20% 27% 7%	2472
	21st to end	Night	35% 8% 20% 26% 12%	2651
August	1st to 10th	Night	43% 9% 13% 26% 9%	2496
	11th to 20th	Night	42% 8% 18% 25% 7%	2792
	21st to end	Night	42% 8% 14% 21% 13% 1	3476
September	1st to 10th	Night	34% 10% 15% 25% 15% 1	1900
	11th to 20th	Night	34% 6% 15% 32% 11% 1	1977
	21st to end	Night	38% 7% 12% 28% 14%	2090
October	1st to 10th	Night	43% 8% 14% 24% 11% 1	3701
	11th to 20th	Night	42% 6% 12% 30% 10%	3860
	21st to end	Night	43% 7% 19% 18% 12% 2	4467
November	1st to 10th	Night	49% 7% 14% 21% 8% 1	2537
	11th to 20th	Night	50% 7% 13% 19% 10% 1	2692
	21st to end	Night	57% 7% 11% 18% 7% 1	2800
December	1st to 10th	Night	61% 8% 12% 14% 4	2737
	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	23% 16% 37% 19% 3 1	180
	21st to end	Day	18% 16% 34% 26% 5% 1	198
February	1st to 10th	Day	27% 24% 34% 13% 1	246
	11th to 20th	Day	19% 17% 43% 19% 2	360
	21st to end	Day	28% 14% 34% 21% 3	382
March	1st to 10th	Day	25% 14% 33% 22% 6%	460
	11th to 20th	Day	20% 21% 32% 22% 3 1	460
	21st to end	Day	25% 17% 32% 16% 8% 1	506
April	1st to 10th	Day	24% 18% 30% 20% 7% 1	460
	11th to 20th	Day	28% 20% 25% 17% 8% 2	452
	21st to end	Day	27% 16% 32% 18% 6% 1	460
May	1st to 10th	Day	22% 15% 34% 21% 6% 1	463
	11th to 20th	Day	19% 14% 32% 24% 10% 1	487
	21st to end	Day	18% 15% 35% 23% 7% 2	529
June	1st to 10th	Day	22% 11% 33% 23% 10% 1	490
	11th to 20th	Day	16% 14% 29% 29% 11% 1	490
	21st to end	Day	22% 12% 26% 27% 10% 2	490
July	1st to 10th	Day	13% 7% 30% 32% 14% 4	485
	11th to 20th	Day	13% 8% 30% 32% 14% 2	484
	21st to end	Day	12% 7% 29% 33% 16% 3	532
August	1st to 10th	Day	14% 8% 23% 34% 18% 2	486
	11th to 20th	Day	12% 5% 24% 33% 18% 9%	479
	21st to end	Day	15% 9% 27% 26% 16% 8%	539
September	1st to 10th	Day	14% 7% 30% 29% 14% 6%	490
	11th to 20th	Day	12% 9% 23% 28% 19% 9%	490
	21st to end	Day	19% 10% 27% 24% 14% 6%	490
October	1st to 10th	Day	23% 12% 27% 24% 12% 3	490
	11th to 20th	Day	20% 17% 32% 20% 10% 2	465
	21st to end	Day	27% 14% 31% 21% 7%	429
November	1st to 10th	Day	24% 14% 32% 23% 7% 1	395
	11th to 20th	Day	21% 17% 36% 17% 8%	305
	21st to end	Day	28% 17% 33% 15% 7% 1	200
December	1st to 10th	Day	25% 18% 23% 25% 8% 1	190
	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% 35% 24% 5%	760
	21st to end	Night	16% 11% 38% 28% 6% 1	836
February	1st to 10th	Night	19% 11% 40% 25% 4 1	760
	11th to 20th	Night	18% 13% 42% 22% 5%	743
	21st to end	Night	21% 11% 38% 27% 4	628
March	1st to 10th	Night	24% 13% 33% 26% 4	760
	11th to 20th	Night	23% 14% 33% 23% 7%	760
	21st to end	Night	20% 10% 38% 25% 6%	836
April	1st to 10th	Night	27% 11% 30% 27% 5%	760
	11th to 20th	Night	25% 12% 32% 25% 5% 1	751
	21st to end	Night	27% 11% 32% 23% 6%	601
May	1st to 10th	Night	23% 10% 33% 28% 6% 1	421
	11th to 20th	Night	22% 9% 31% 30% 8%	374
	21st to end	Night	20% 7% 39% 27% 8%	411
June	1st to 10th	Night	23% 6% 31% 31% 9%	380
	11th to 20th	Night	18% 8% 29% 32% 12%	380
	21st to end	Night	21% 7% 27% 32% 13%	380
July	1st to 10th	Night	9% 7% 32% 37% 14% 1	370
	11th to 20th	Night	12% 4 25% 45% 14%	368
	21st to end	Night	12% 3 25% 44% 15% 1	416
August	1st to 10th	Night	14% 4 16% 47% 18%	378
	11th to 20th	Night	14% 4 23% 34% 22% 2	544
	21st to end	Night	15% 6% 25% 34% 19% 2	836
September	1st to 10th	Night	14% 4 27% 39% 15% 1	760
	11th to 20th	Night	14% 6% 23% 34% 22% 2	760
	21st to end	Night	19% 5% 29% 31% 14% 2	760
October	1st to 10th	Night	21% 6% 30% 31% 10% 1	760
	11th to 20th	Night	23% 8% 30% 29% 9% 1	760
	21st to end	Night	27% 10% 33% 25% 6%	836
November	1st to 10th	Night	21% 12% 33% 25% 8% 1	780
	11th to 20th	Night	24% 10% 35% 22% 9% 1	800
	21st to end	Night	27% 13% 33% 20% 7% 1	800
December	1st to 10th	Night	28% 10% 33% 23% 7%	783
	11th to 20th	Night	27% 13% 33% 22% 4 1	760
	21st to end	Night	31% 12% 32% 19% 5%	836

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

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