Mont-Laurier
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mont-Laurier clear sky chart from 2005-11-06 to 2024-11-04.

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% 12% 4 9% 5% 5% 4 4 5% 6% 29%	101584
	Night	17% 13% 4 9% 5% 5% 4 3 5% 6% 28%	97427
Transparency	Day	57% 2 11% 21% 9% 1	105055
	Night	58% 2 11% 19% 8% 1	102045
Seeing	Day	26% 12% 30% 20% 9% 2	14398
	Night	26% 10% 27% 26% 10% 1	23405

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% 20% 8% 18% 7% 5% 4 2 3 3 14%	2517
	11th to 20th	Day	13% 15% 8% 21% 8% 3 3 2 3 5% 18%	2520
	21st to end	Day	11% 19% 9% 13% 6% 6% 5% 4 5% 5% 17%	2786
February	1st to 10th	Day	10% 19% 7% 14% 10% 6% 4 3 4 5% 18%	1710
	11th to 20th	Day	12% 20% 6% 12% 7% 5% 4 3 4 5% 23%	1663
	21st to end	Day	18% 16% 6% 9% 7% 5% 4 3 3 6% 23%	1568
March	1st to 10th	Day	15% 18% 5% 9% 5% 4 4 3 5% 5% 26%	3116
	11th to 20th	Day	13% 19% 7% 12% 6% 4 4 3 3 4 25%	3439
	21st to end	Day	13% 8% 3 9% 7% 4 5% 4 5% 6% 36%	4056
April	1st to 10th	Day	21% 16% 4 8% 5% 3 4 3 3 5% 29%	2280
	11th to 20th	Day	22% 12% 4 7% 4 5% 4 3 5% 5% 31%	2254
	21st to end	Day	21% 12% 4 8% 4 5% 4 3 4 4 31%	2475
May	1st to 10th	Day	20% 11% 4 8% 5% 6% 5% 4 5% 6% 27%	4426
	11th to 20th	Day	19% 9% 2 7% 5% 5% 5% 3 6% 7% 32%	4398
	21st to end	Day	17% 8% 3 7% 5% 5% 5% 4 5% 7% 33%	4837
June	1st to 10th	Day	22% 8% 3 8% 6% 5% 6% 4 5% 5% 27%	2660
	11th to 20th	Day	15% 6% 2 7% 5% 5% 5% 5% 7% 7% 35%	2660
	21st to end	Day	21% 8% 3 8% 5% 4 5% 4 6% 7% 28%	2660
July	1st to 10th	Day	15% 7% 3 7% 5% 6% 5% 5% 7% 10% 30%	4440
	11th to 20th	Day	15% 8% 2 7% 5% 5% 5% 4 6% 8% 35%	4440
	21st to end	Day	12% 7% 3 6% 4 4 4 4 6% 8% 42%	4814
August	1st to 10th	Day	16% 6% 3 9% 6% 6% 6% 5% 7% 8% 29%	4423
	11th to 20th	Day	17% 8% 3 6% 5% 5% 5% 4 6% 7% 34%	4052
	21st to end	Day	13% 7% 2 7% 6% 4 5% 4 7% 9% 35%	4180
September	1st to 10th	Day	17% 6% 2 7% 4 4 3 3 5% 7% 40%	2280
	11th to 20th	Day	16% 8% 2 7% 4 4 4 3 5% 6% 41%	2271
	21st to end	Day	22% 7% 3 7% 4 3 4 3 5% 8% 35%	2042
October	1st to 10th	Day	21% 10% 3 7% 4 5% 5% 4 4 7% 30%	1900
	11th to 20th	Day	26% 12% 4 9% 6% 4 4 3 4 5% 23%	1900
	21st to end	Day	26% 14% 4 9% 4 4 5% 3 4 6% 21%	1900
November	1st to 10th	Day	17% 14% 4 8% 5% 3 4 3 5% 7% 30%	1679
	11th to 20th	Day	21% 17% 5% 11% 6% 4 4 4 4 5% 19%	1520
	21st to end	Day	23% 20% 7% 13% 7% 3 4 2 2 4 16%	1520
December	1st to 10th	Day	22% 22% 6% 13% 7% 4 3 3 3 4 14%	1520
	11th to 20th	Day	20% 18% 6% 13% 6% 5% 4 3 5% 5% 16%	1906
	21st to end	Day	21% 21% 7% 14% 6% 3 3 2 3 4 16%	2772
January	1st to 10th	Night	16% 21% 8% 13% 6% 4 4 3 4 4 19%	4429
	11th to 20th	Night	14% 15% 6% 16% 10% 5% 4 4 4 5% 18%	4440
	21st to end	Night	11% 17% 9% 14% 7% 7% 5% 3 4 4 18%	4855
February	1st to 10th	Night	12% 16% 7% 13% 9% 6% 5% 4 4 5% 22%	2470
	11th to 20th	Night	12% 15% 6% 14% 8% 6% 5% 3 4 5% 22%	2403
	21st to end	Night	13% 17% 5% 10% 6% 6% 5% 3 5% 5% 25%	1885
March	1st to 10th	Night	19% 15% 4 8% 6% 5% 4 3 4 4 28%	3724
	11th to 20th	Night	15% 20% 6% 11% 5% 4 4 3 4 5% 24%	3517
	21st to end	Night	12% 10% 4 9% 6% 5% 4 4 5% 7% 35%	3575
April	1st to 10th	Night	22% 13% 4 7% 6% 4 4 3 4 5% 29%	1900
	11th to 20th	Night	19% 9% 2 6% 5% 4 4 3 5% 5% 37%	1875
	21st to end	Night	22% 10% 2 9% 5% 4 4 2 5% 4 34%	1719
May	1st to 10th	Night	20% 11% 4 7% 4 4 5% 3 6% 6% 30%	2514
	11th to 20th	Night	18% 9% 2 8% 5% 4 4 4 5% 6% 33%	2495
	21st to end	Night	18% 8% 3 7% 5% 5% 5% 4 5% 6% 34%	2738
June	1st to 10th	Night	17% 8% 3 7% 6% 4 6% 4 8% 8% 30%	1520
	11th to 20th	Night	16% 6% 3 7% 5% 4 4 3 6% 7% 39%	1520
	21st to end	Night	19% 7% 3 6% 5% 4 4 3 6% 7% 35%	1520
July	1st to 10th	Night	14% 8% 3 9% 5% 6% 6% 4 7% 6% 32%	2520
	11th to 20th	Night	15% 7% 3 6% 4 4 5% 4 6% 7% 38%	2520
	21st to end	Night	11% 5% 2 6% 4 4 4 4 6% 7% 46%	2739
August	1st to 10th	Night	13% 6% 3 7% 5% 5% 5% 4 6% 8% 38%	2506
	11th to 20th	Night	19% 6% 3 6% 4 4 4 4 7% 7% 36%	2746
	21st to end	Night	20% 7% 3 7% 4 3 4 4 6% 7% 37%	3471
September	1st to 10th	Night	16% 6% 2 6% 4 4 4 3 5% 6% 44%	1900
	11th to 20th	Night	17% 6% 2 6% 3 3 3 4 4 7% 45%	1909
	21st to end	Night	19% 8% 2 6% 4 4 4 3 4 6% 40%	2137
October	1st to 10th	Night	21% 9% 2 6% 4 4 4 3 4 6% 37%	2280
	11th to 20th	Night	25% 12% 3 9% 5% 4 4 3 5% 5% 26%	2280
	21st to end	Night	26% 13% 3 8% 4 4 5% 3 5% 5% 23%	2698
November	1st to 10th	Night	19% 15% 4 8% 4 4 4 3 5% 5% 27%	2470
	11th to 20th	Night	19% 15% 4 11% 6% 5% 4 3 4 5% 22%	2660
	21st to end	Night	23% 18% 6% 12% 6% 4 3 3 5% 4 16%	2660
December	1st to 10th	Night	21% 21% 8% 12% 5% 6% 4 3 4 4 13%	2660
	11th to 20th	Night	22% 18% 6% 10% 5% 4 3 3 4 5% 20%	3288
	21st to end	Night	22% 22% 5% 12% 5% 4 4 2 3 3 17%	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	79% 1 7% 9% 4	2518
	11th to 20th	Day	72% 1 6% 15% 6%	2520
	21st to end	Day	70% 2 9% 12% 6% 1	2786
February	1st to 10th	Day	70% 2 5% 14% 7% 1	1710
	11th to 20th	Day	66% 1 9% 13% 10% 1	1672
	21st to end	Day	65% 1 7% 15% 10% 1	1568
March	1st to 10th	Day	61% 1 10% 15% 12% 1	3119
	11th to 20th	Day	66% 2 8% 14% 10% 2	3439
	21st to end	Day	50% 2 6% 24% 16% 2	4056
April	1st to 10th	Day	60% 2 7% 17% 11% 3	2280
	11th to 20th	Day	57% 2 6% 22% 11% 2	2254
	21st to end	Day	58% 2 8% 17% 13% 3	2475
May	1st to 10th	Day	59% 2 6% 21% 10% 1	4440
	11th to 20th	Day	53% 1 10% 25% 10% 1	4402
	21st to end	Day	52% 2 9% 20% 16% 1	4837
June	1st to 10th	Day	58% 2 8% 20% 11% 1	2660
	11th to 20th	Day	46% 3 11% 26% 12% 2	2660
	21st to end	Day	54% 4 12% 20% 10%	2660
July	1st to 10th	Day	49% 2 14% 27% 7%	4370
	11th to 20th	Day	49% 2 16% 28% 6%	4365
	21st to end	Day	42% 2 17% 30% 9%	4661
August	1st to 10th	Day	52% 4 14% 24% 7%	4409
	11th to 20th	Day	49% 2 17% 26% 5%	4092
	21st to end	Day	46% 3 14% 25% 12% 1	4180
September	1st to 10th	Day	45% 2 14% 26% 12% 1	2280
	11th to 20th	Day	44% 3 14% 27% 11% 1	2271
	21st to end	Day	49% 3 13% 26% 9%	2042
October	1st to 10th	Day	57% 1 9% 27% 5%	3160
	11th to 20th	Day	59% 3 12% 21% 5%	3140
	21st to end	Day	61% 3 17% 14% 5% 1	3112
November	1st to 10th	Day	55% 2 13% 22% 7% 1	1679
	11th to 20th	Day	68% 3 12% 11% 6%	1520
	21st to end	Day	76% 2 9% 9% 5%	1520
December	1st to 10th	Day	76% 2 8% 11% 3	1520
	11th to 20th	Day	72% 2 7% 13% 6%	1906
	21st to end	Day	75% 1 6% 15% 3	2772
January	1st to 10th	Night	72% 1 13% 11% 2	4429
	11th to 20th	Night	71% 1 10% 13% 4 1	4440
	21st to end	Night	71% 2 9% 10% 7%	4855
February	1st to 10th	Night	67% 2 8% 16% 6% 1	2470
	11th to 20th	Night	67% 2 7% 16% 7% 1	2405
	21st to end	Night	62% 2 8% 18% 10% 1	1885
March	1st to 10th	Night	61% 2 11% 13% 11% 2	3734
	11th to 20th	Night	65% 1 8% 16% 8% 1	3518
	21st to end	Night	51% 2 7% 23% 15% 3	3575
April	1st to 10th	Night	58% 2 7% 18% 14% 2	1900
	11th to 20th	Night	51% 2 7% 24% 15% 2	1875
	21st to end	Night	55% 2 7% 18% 15% 3	1719
May	1st to 10th	Night	56% 1 10% 20% 10% 2	2520
	11th to 20th	Night	52% 2 11% 21% 11% 2	2496
	21st to end	Night	52% 2 9% 22% 14% 1	2739
June	1st to 10th	Night	50% 3 12% 23% 11% 1	1520
	11th to 20th	Night	46% 2 11% 25% 13% 3	1520
	21st to end	Night	49% 4 14% 22% 11% 1	1520
July	1st to 10th	Night	51% 3 16% 21% 9%	2480
	11th to 20th	Night	46% 2 18% 26% 6%	2472
	21st to end	Night	37% 3 18% 32% 11%	2651
August	1st to 10th	Night	46% 3 16% 27% 8%	2496
	11th to 20th	Night	47% 3 18% 26% 6%	2772
	21st to end	Night	47% 2 14% 25% 10% 2	3471
September	1st to 10th	Night	42% 3 14% 28% 12%	1900
	11th to 20th	Night	40% 2 16% 32% 9%	1909
	21st to end	Night	47% 3 12% 29% 9%	2137
October	1st to 10th	Night	49% 2 14% 25% 10%	3800
	11th to 20th	Night	56% 2 12% 23% 6%	3779
	21st to end	Night	59% 2 16% 14% 9% 1	4436
November	1st to 10th	Night	60% 3 12% 18% 7%	2470
	11th to 20th	Night	66% 2 10% 14% 7% 1	2660
	21st to end	Night	72% 3 9% 13% 3	2660
December	1st to 10th	Night	76% 3 7% 10% 3	2660
	11th to 20th	Night	69% 2 7% 16% 6% 1	3288
	21st to end	Night	74% 1 6% 14% 4	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	24% 14% 39% 17% 6%	180
	11th to 20th	Day	26% 13% 36% 18% 7% 1	180
	21st to end	Day	25% 14% 33% 22% 6%	204
February	1st to 10th	Day	27% 23% 37% 9% 3	270
	11th to 20th	Day	26% 22% 41% 10% 1	270
	21st to end	Day	32% 18% 33% 14% 3	380
March	1st to 10th	Day	24% 18% 33% 17% 7% 1	460
	11th to 20th	Day	28% 16% 34% 18% 3 2	460
	21st to end	Day	29% 18% 30% 16% 6% 1	506
April	1st to 10th	Day	32% 15% 28% 18% 6% 2	460
	11th to 20th	Day	34% 14% 25% 15% 11% 2	452
	21st to end	Day	32% 16% 29% 16% 6% 1	460
May	1st to 10th	Day	28% 13% 33% 19% 6% 2	463
	11th to 20th	Day	26% 12% 29% 22% 9% 2	487
	21st to end	Day	24% 15% 34% 19% 7% 2	529
June	1st to 10th	Day	29% 10% 32% 21% 7% 1	490
	11th to 20th	Day	21% 10% 36% 17% 13% 2	490
	21st to end	Day	26% 9% 28% 25% 11% 1	490
July	1st to 10th	Day	16% 8% 33% 31% 9% 4	485
	11th to 20th	Day	19% 9% 30% 29% 11% 2	484
	21st to end	Day	17% 5% 30% 32% 14% 3	532
August	1st to 10th	Day	21% 6% 27% 29% 14% 3	486
	11th to 20th	Day	21% 4 25% 27% 16% 7%	479
	21st to end	Day	19% 12% 28% 21% 14% 6%	539
September	1st to 10th	Day	23% 8% 28% 24% 11% 7%	490
	11th to 20th	Day	20% 9% 21% 24% 18% 8%	490
	21st to end	Day	24% 11% 23% 21% 14% 7%	490
October	1st to 10th	Day	29% 13% 24% 19% 13% 3	490
	11th to 20th	Day	35% 13% 28% 17% 7% 2	490
	21st to end	Day	35% 11% 28% 19% 6% 1	439
November	1st to 10th	Day	31% 13% 30% 19% 6%	355
	11th to 20th	Day	29% 16% 38% 9% 5% 2	180
	21st to end	Day	30% 21% 33% 12% 4 1	180
December	1st to 10th	Day	34% 12% 32% 17% 5%	180
	11th to 20th	Day	27% 23% 34% 12% 3 1	180
	21st to end	Day	31% 16% 32% 14% 6% 2	198
January	1st to 10th	Night	31% 11% 31% 21% 6%	760
	11th to 20th	Night	30% 13% 26% 25% 6%	760
	21st to end	Night	19% 11% 31% 30% 8% 1	836
February	1st to 10th	Night	21% 14% 34% 24% 6% 1	760
	11th to 20th	Night	21% 14% 37% 22% 5% 1	743
	21st to end	Night	22% 16% 31% 26% 5%	628
March	1st to 10th	Night	25% 13% 30% 27% 5%	760
	11th to 20th	Night	27% 13% 29% 24% 6% 1	760
	21st to end	Night	22% 14% 33% 23% 8% 1	836
April	1st to 10th	Night	30% 13% 23% 27% 7%	760
	11th to 20th	Night	26% 12% 28% 23% 10% 1	751
	21st to end	Night	30% 10% 27% 22% 9% 1	579
May	1st to 10th	Night	26% 6% 30% 28% 9% 1	380
	11th to 20th	Night	24% 9% 27% 30% 10%	374
	21st to end	Night	21% 8% 33% 29% 9%	411
June	1st to 10th	Night	23% 5% 33% 31% 8%	380
	11th to 20th	Night	21% 5% 24% 34% 15%	380
	21st to end	Night	22% 5% 21% 38% 14% 1	380
July	1st to 10th	Night	14% 3 24% 43% 16%	370
	11th to 20th	Night	14% 3 21% 41% 19% 1	368
	21st to end	Night	12% 4 23% 43% 16% 2	416
August	1st to 10th	Night	15% 3 18% 41% 22% 1	378
	11th to 20th	Night	18% 3 18% 31% 28% 3	537
	21st to end	Night	20% 6% 22% 31% 19% 2	831
September	1st to 10th	Night	21% 4 24% 34% 16% 1	760
	11th to 20th	Night	22% 5% 20% 30% 22% 2	760
	21st to end	Night	24% 7% 23% 27% 17% 2	760
October	1st to 10th	Night	26% 8% 28% 25% 12% 1	760
	11th to 20th	Night	35% 9% 25% 21% 8% 1	760
	21st to end	Night	35% 10% 24% 25% 5% 1	836
November	1st to 10th	Night	30% 12% 26% 24% 7% 1	755
	11th to 20th	Night	30% 14% 28% 19% 8% 1	760
	21st to end	Night	35% 15% 24% 20% 5% 1	760
December	1st to 10th	Night	33% 13% 27% 20% 6% 1	760
	11th to 20th	Night	28% 15% 30% 19% 6% 1	760
	21st to end	Night	35% 12% 26% 22% 4 1	836

Page generated at 2024-11-01 22:47:43. Version ac07

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