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 2025-08-05.

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 10% 6% 5% 5% 4 5% 6% 28%	126104
	Night	17% 13% 5% 10% 6% 5% 4 3 5% 6% 27%	121942
Transparency	Day	58% 2 10% 20% 9% 1	129557
	Night	60% 2 10% 18% 8% 1	126576
Seeing	Day	26% 13% 30% 20% 9% 2	15303
	Night	26% 10% 27% 26% 10% 1	24296

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% 20% 8% 21% 8% 7% 4 2 3 3 12%	3597
	11th to 20th	Day	11% 18% 8% 21% 9% 3 3 2 4 5% 16%	3570
	21st to end	Day	8% 16% 10% 15% 6% 5% 5% 4 5% 7% 20%	3988
February	1st to 10th	Day	10% 18% 7% 15% 10% 6% 4 3 4 5% 19%	1800
	11th to 20th	Day	12% 20% 6% 13% 7% 5% 3 3 4 5% 23%	1753
	21st to end	Day	18% 16% 6% 10% 8% 5% 4 3 3 6% 23%	1648
March	1st to 10th	Day	16% 18% 5% 12% 6% 5% 4 3 5% 5% 22%	4476
	11th to 20th	Day	14% 15% 6% 11% 6% 5% 5% 3 4 5% 27%	4925
	21st to end	Day	17% 13% 4 9% 6% 4 4 3 4 5% 32%	5818
April	1st to 10th	Day	21% 16% 4 8% 5% 3 4 3 3 5% 29%	2400
	11th to 20th	Day	22% 12% 4 7% 4 4 4 3 5% 5% 31%	2374
	21st to end	Day	21% 13% 4 8% 4 5% 4 3 4 4 31%	2605
May	1st to 10th	Day	22% 11% 3 8% 5% 5% 5% 4 5% 6% 25%	6346
	11th to 20th	Day	18% 9% 3 9% 6% 5% 5% 3 6% 6% 30%	6318
	21st to end	Day	21% 10% 3 8% 5% 5% 5% 4 5% 6% 29%	6949
June	1st to 10th	Day	22% 8% 3 8% 6% 5% 5% 4 5% 5% 28%	2800
	11th to 20th	Day	15% 6% 2 7% 5% 5% 5% 5% 7% 7% 35%	2800
	21st to end	Day	21% 7% 3 8% 5% 4 5% 4 6% 7% 29%	2800
July	1st to 10th	Day	17% 7% 3 7% 5% 5% 5% 5% 7% 10% 29%	6360
	11th to 20th	Day	13% 7% 2 7% 5% 5% 5% 4 6% 8% 38%	6360
	21st to end	Day	10% 6% 3 6% 4 4 5% 4 7% 10% 41%	6926
August	1st to 10th	Day	16% 6% 3 9% 6% 6% 6% 5% 7% 8% 29%	4479
	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% 6% 29%	1741
	11th to 20th	Day	20% 17% 5% 11% 6% 4 5% 4 4 5% 19%	1600
	21st to end	Day	23% 21% 7% 12% 7% 3 4 2 2 4 15%	1600
December	1st to 10th	Day	19% 23% 9% 14% 8% 4 3 3 4 4 11%	2600
	11th to 20th	Day	17% 19% 6% 13% 8% 5% 5% 3 4 4 17%	2986
	21st to end	Day	18% 19% 6% 13% 6% 5% 5% 3 3 4 17%	3960
January	1st to 10th	Night	12% 23% 9% 16% 7% 4 4 3 3 3 15%	6349
	11th to 20th	Night	12% 16% 7% 18% 11% 6% 4 3 4 5% 15%	6315
	21st to end	Night	8% 16% 9% 15% 7% 7% 6% 4 4 5% 19%	6953
February	1st to 10th	Night	11% 15% 6% 13% 8% 6% 4 4 4 5% 22%	2600
	11th to 20th	Night	12% 15% 6% 14% 8% 6% 5% 3 4 5% 22%	2533
	21st to end	Night	12% 17% 6% 11% 6% 6% 4 3 5% 5% 25%	1981
March	1st to 10th	Night	19% 17% 5% 10% 6% 5% 4 3 4 4 24%	5364
	11th to 20th	Night	12% 15% 5% 11% 7% 5% 5% 4 5% 7% 25%	5031
	21st to end	Night	15% 12% 4 9% 6% 5% 4 4 5% 6% 30%	5113
April	1st to 10th	Night	21% 13% 4 8% 6% 4 4 3 4 5% 29%	2000
	11th to 20th	Night	19% 10% 3 6% 5% 4 4 3 5% 5% 36%	1975
	21st to end	Night	23% 9% 2 9% 5% 3 4 2 5% 5% 33%	1809
May	1st to 10th	Night	21% 11% 4 9% 4 4 4 3 6% 6% 27%	3594
	11th to 20th	Night	17% 9% 3 9% 5% 5% 5% 4 5% 7% 33%	3575
	21st to end	Night	21% 10% 3 8% 5% 5% 5% 3 5% 6% 30%	3926
June	1st to 10th	Night	17% 8% 3 7% 6% 4 5% 4 8% 8% 31%	1600
	11th to 20th	Night	16% 6% 3 7% 5% 4 4 3 6% 7% 39%	1600
	21st to end	Night	19% 7% 3 6% 5% 4 4 3 6% 7% 35%	1600
July	1st to 10th	Night	14% 7% 3 8% 5% 6% 6% 5% 7% 7% 30%	3600
	11th to 20th	Night	13% 6% 3 7% 5% 4 5% 4 5% 8% 41%	3600
	21st to end	Night	11% 5% 2 6% 4 4 4 4 6% 8% 47%	3926
August	1st to 10th	Night	13% 6% 3 7% 5% 5% 5% 4 6% 8% 38%	2538
	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	20% 15% 4 9% 4 4 4 3 5% 5% 27%	2555
	11th to 20th	Night	19% 15% 5% 11% 6% 5% 4 3 4 5% 23%	2800
	21st to end	Night	22% 19% 6% 12% 6% 4 3 3 5% 4 16%	2800
December	1st to 10th	Night	18% 19% 7% 16% 8% 6% 5% 3 4 4 9%	4580
	11th to 20th	Night	23% 15% 6% 12% 6% 4 3 3 3 4 21%	5208
	21st to end	Night	21% 21% 5% 11% 6% 4 4 3 4 5% 17%	6996

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	82% 1 5% 9% 4	3598
	11th to 20th	Day	74% 1 5% 13% 8%	3600
	21st to end	Day	65% 2 7% 15% 10% 1	3988
February	1st to 10th	Day	70% 2 5% 14% 8% 1	1800
	11th to 20th	Day	67% 1 9% 13% 9% 1	1762
	21st to end	Day	66% 1 7% 15% 11%	1648
March	1st to 10th	Day	66% 1 7% 11% 12% 2	4479
	11th to 20th	Day	62% 2 12% 13% 10% 1	4925
	21st to end	Day	56% 1 5% 20% 16% 1	5818
April	1st to 10th	Day	60% 2 7% 17% 11% 3	2400
	11th to 20th	Day	57% 2 6% 22% 11% 2	2374
	21st to end	Day	58% 2 8% 16% 13% 3	2605
May	1st to 10th	Day	61% 2 5% 20% 10% 2	6357
	11th to 20th	Day	56% 1 10% 22% 10% 1	6322
	21st to end	Day	58% 1 8% 18% 14% 1	6949
June	1st to 10th	Day	58% 2 7% 20% 11% 1	2800
	11th to 20th	Day	46% 3 11% 27% 12% 2	2800
	21st to end	Day	54% 4 13% 20% 10%	2800
July	1st to 10th	Day	51% 2 14% 27% 6%	6290
	11th to 20th	Day	45% 1 16% 31% 6%	6285
	21st to end	Day	40% 1 17% 34% 8%	6728
August	1st to 10th	Day	52% 4 14% 24% 7%	4465
	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	56% 2 13% 21% 6% 1	1741
	11th to 20th	Day	68% 3 11% 12% 7%	1600
	21st to end	Day	76% 2 9% 8% 4	1600
December	1st to 10th	Day	81% 1 6% 11% 2	2600
	11th to 20th	Day	73% 2 5% 14% 6%	2986
	21st to end	Day	73% 2 5% 17% 3	3960
January	1st to 10th	Night	77% 1 9% 10% 2	6349
	11th to 20th	Night	75% 1 8% 11% 4	6360
	21st to end	Night	69% 2 6% 11% 11%	6953
February	1st to 10th	Night	66% 2 8% 16% 7% 1	2600
	11th to 20th	Night	67% 2 7% 16% 7% 1	2535
	21st to end	Night	62% 2 8% 18% 9% 1	1981
March	1st to 10th	Night	66% 2 7% 10% 12% 3	5374
	11th to 20th	Night	61% 2 12% 16% 8% 2	5032
	21st to end	Night	57% 2 5% 22% 11% 2	5113
April	1st to 10th	Night	59% 2 6% 18% 14% 2	2000
	11th to 20th	Night	51% 2 6% 24% 15% 2	1975
	21st to end	Night	55% 2 7% 18% 15% 3	1809
May	1st to 10th	Night	59% 2 8% 19% 11% 2	3600
	11th to 20th	Night	53% 3 11% 21% 11% 2	3576
	21st to end	Night	57% 1 9% 18% 12% 1	3927
June	1st to 10th	Night	50% 3 12% 24% 12% 1	1600
	11th to 20th	Night	46% 2 11% 26% 13% 3	1600
	21st to end	Night	49% 4 14% 22% 11% 1	1600
July	1st to 10th	Night	51% 3 16% 23% 7%	3560
	11th to 20th	Night	44% 2 17% 31% 6%	3552
	21st to end	Night	37% 2 16% 34% 10%	3809
August	1st to 10th	Night	46% 3 16% 27% 8%	2528
	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	61% 3 12% 18% 7%	2555
	11th to 20th	Night	65% 2 10% 14% 8% 1	2800
	21st to end	Night	73% 3 8% 13% 3	2800
December	1st to 10th	Night	81% 2 8% 7% 2	4580
	11th to 20th	Night	70% 1 5% 15% 8%	5208
	21st to end	Night	72% 2 4 13% 8%	6996

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	23% 15% 42% 16% 5%	200
	11th to 20th	Day	27% 13% 36% 17% 7% 1	200
	21st to end	Day	24% 15% 33% 22% 6%	227
February	1st to 10th	Day	27% 24% 38% 9% 2	300
	11th to 20th	Day	27% 22% 41% 9% 1	300
	21st to end	Day	31% 17% 34% 15% 3	412
March	1st to 10th	Day	25% 19% 32% 17% 6% 1	500
	11th to 20th	Day	28% 17% 33% 18% 3 1	500
	21st to end	Day	31% 17% 30% 15% 5% 1	550
April	1st to 10th	Day	33% 15% 27% 18% 6% 2	500
	11th to 20th	Day	35% 14% 24% 15% 11% 2	492
	21st to end	Day	32% 16% 30% 15% 6% 1	500
May	1st to 10th	Day	29% 13% 32% 18% 5% 2	503
	11th to 20th	Day	26% 12% 29% 21% 9% 2	527
	21st to end	Day	26% 14% 33% 19% 7% 2	573
June	1st to 10th	Day	29% 10% 32% 21% 7% 1	530
	11th to 20th	Day	22% 11% 36% 18% 12% 2	530
	21st to end	Day	26% 9% 30% 24% 10% 1	530
July	1st to 10th	Day	16% 8% 35% 30% 9% 3	525
	11th to 20th	Day	18% 8% 31% 29% 11% 2	524
	21st to end	Day	16% 7% 31% 31% 13% 3	576
August	1st to 10th	Day	20% 6% 27% 30% 14% 3	502
	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	33% 13% 30% 19% 5%	375
	11th to 20th	Day	29% 17% 37% 11% 5% 2	200
	21st to end	Day	32% 19% 34% 12% 4 1	200
December	1st to 10th	Day	33% 13% 30% 19% 5% 1	200
	11th to 20th	Day	28% 23% 34% 11% 4 1	200
	21st to end	Day	30% 15% 32% 14% 6% 2	220
January	1st to 10th	Night	31% 12% 32% 21% 5%	800
	11th to 20th	Night	30% 12% 26% 25% 6%	800
	21st to end	Night	19% 11% 31% 30% 8% 1	880
February	1st to 10th	Night	20% 15% 35% 24% 6% 1	800
	11th to 20th	Night	21% 15% 37% 21% 5% 1	783
	21st to end	Night	22% 15% 31% 26% 5%	660
March	1st to 10th	Night	26% 13% 29% 26% 5%	800
	11th to 20th	Night	26% 14% 30% 24% 6% 1	800
	21st to end	Night	23% 15% 32% 22% 7% 1	880
April	1st to 10th	Night	30% 13% 23% 27% 7%	800
	11th to 20th	Night	26% 12% 28% 23% 10% 1	791
	21st to end	Night	31% 10% 27% 22% 9% 1	609
May	1st to 10th	Night	27% 6% 30% 28% 9% 1	400
	11th to 20th	Night	23% 8% 28% 30% 10%	394
	21st to end	Night	22% 7% 32% 30% 9%	433
June	1st to 10th	Night	22% 5% 33% 33% 8%	400
	11th to 20th	Night	21% 6% 24% 35% 14%	400
	21st to end	Night	22% 5% 22% 37% 14% 1	400
July	1st to 10th	Night	15% 3 23% 43% 15%	390
	11th to 20th	Night	14% 3 21% 42% 19% 1	388
	21st to end	Night	12% 4 24% 42% 16% 2	438
August	1st to 10th	Night	15% 3 18% 42% 22% 1	386
	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	31% 11% 26% 23% 7% 1	780
	11th to 20th	Night	30% 13% 28% 20% 8% 1	800
	21st to end	Night	35% 15% 24% 20% 5% 1	800
December	1st to 10th	Night	33% 13% 28% 20% 6% 1	800
	11th to 20th	Night	29% 15% 30% 20% 6% 1	800
	21st to end	Night	35% 11% 25% 23% 5% 1	880

Page generated at 2025-08-02 01:32:23. Version ac07

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