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 2024-04-10.

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	18% 12% 5% 8% 7% 3 5% 4 5% 6% 28%	82921
	Night	17% 13% 5% 8% 7% 3 4 4 5% 6% 28%	85845
Transparency	Day	58% 2 10% 19% 9% 1	82626
	Night	60% 2 10% 18% 8% 1	85674
Seeing	Day	26% 13% 30% 20% 9% 2	13580
	Night	26% 10% 27% 26% 10% 1	22800

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% 19% 9% 17% 9% 4 4 2 2 3 14%	2517
	11th to 20th	Day	14% 15% 8% 18% 10% 2 4 3 3 4 19%	2520
	21st to end	Day	11% 19% 9% 12% 7% 5% 5% 4 5% 5% 17%	2786
February	1st to 10th	Day	10% 18% 8% 12% 11% 5% 5% 4 4 5% 18%	1710
	11th to 20th	Day	12% 19% 7% 11% 7% 4 4 3 4 5% 23%	1663
	21st to end	Day	18% 15% 6% 9% 7% 4 4 4 3 5% 23%	1568
March	1st to 10th	Day	15% 17% 5% 9% 6% 4 4 4 5% 5% 26%	3116
	11th to 20th	Day	13% 18% 7% 11% 7% 4 4 4 3 4 25%	3439
	21st to end	Day	13% 8% 4 8% 8% 3 5% 5% 5% 7% 36%	4056
April	1st to 10th	Day	22% 15% 4 7% 6% 3 3 3 3 5% 29%	2270
	11th to 20th	Day	22% 11% 4 6% 5% 3 4 4 4 5% 32%	2134
	21st to end	Day	22% 11% 4 7% 5% 3 4 4 4 5% 31%	2344
May	1st to 10th	Day	21% 10% 4 6% 6% 3 4 4 4 7% 31%	2520
	11th to 20th	Day	21% 9% 3 5% 6% 4 4 3 5% 6% 34%	2478
	21st to end	Day	18% 8% 3 6% 6% 4 5% 5% 5% 7% 34%	2725
June	1st to 10th	Day	22% 8% 4 6% 7% 4 6% 5% 5% 6% 28%	2520
	11th to 20th	Day	16% 5% 2 6% 6% 3 6% 6% 6% 8% 36%	2520
	21st to end	Day	21% 7% 3 7% 6% 3 6% 5% 6% 7% 29%	2520
July	1st to 10th	Day	16% 6% 3 5% 5% 4 5% 6% 6% 10% 35%	2520
	11th to 20th	Day	14% 7% 3 6% 6% 4 6% 5% 6% 9% 34%	2520
	21st to end	Day	13% 7% 3 7% 6% 4 6% 6% 6% 8% 34%	2744
August	1st to 10th	Day	15% 7% 3 7% 7% 4 6% 6% 6% 8% 31%	2506
	11th to 20th	Day	15% 8% 4 5% 6% 4 5% 5% 6% 7% 36%	2312
	21st to end	Day	15% 8% 2 6% 7% 3 5% 5% 6% 7% 34%	2376
September	1st to 10th	Day	17% 6% 3 6% 6% 3 4 4 5% 7% 39%	2160
	11th to 20th	Day	17% 8% 3 7% 5% 3 4 5% 5% 6% 39%	2152
	21st to end	Day	22% 7% 3 6% 5% 3 4 4 5% 8% 35%	1935
October	1st to 10th	Day	22% 9% 3 6% 6% 4 5% 5% 4 7% 30%	1800
	11th to 20th	Day	28% 11% 5% 8% 7% 4 4 4 4 6% 22%	1800
	21st to end	Day	28% 13% 4 8% 5% 3 5% 5% 4 5% 21%	1800
November	1st to 10th	Day	17% 13% 5% 8% 6% 3 4 4 5% 7% 30%	1652
	11th to 20th	Day	22% 15% 6% 10% 7% 3 5% 5% 4 5% 19%	1520
	21st to end	Day	23% 19% 7% 11% 8% 2 4 2 2 4 16%	1520
December	1st to 10th	Day	23% 20% 7% 12% 8% 3 3 3 3 4 14%	1520
	11th to 20th	Day	21% 16% 7% 11% 8% 4 4 4 5% 5% 16%	1906
	21st to end	Day	21% 20% 7% 12% 8% 2 3 3 2 4 16%	2772
January	1st to 10th	Night	16% 20% 9% 11% 7% 3 4 4 4 4 19%	4429
	11th to 20th	Night	14% 14% 6% 13% 13% 4 4 4 4 5% 18%	4440
	21st to end	Night	11% 17% 10% 13% 8% 5% 6% 4 4 4 18%	4855
February	1st to 10th	Night	12% 14% 7% 11% 10% 5% 5% 5% 4 5% 22%	2470
	11th to 20th	Night	12% 14% 7% 13% 8% 4 7% 3 4 5% 23%	2403
	21st to end	Night	13% 16% 6% 9% 7% 4 6% 4 5% 6% 25%	1885
March	1st to 10th	Night	19% 14% 5% 7% 6% 3 5% 3 4 5% 28%	3724
	11th to 20th	Night	15% 18% 6% 10% 6% 3 4 4 4 5% 24%	3517
	21st to end	Night	12% 9% 4 8% 7% 4 4 5% 5% 7% 35%	3575
April	1st to 10th	Night	22% 11% 4 6% 6% 3 4 4 4 5% 29%	1900
	11th to 20th	Night	20% 8% 3 5% 5% 3 5% 4 5% 5% 37%	1775
	21st to end	Night	22% 9% 3 8% 6% 3 4 3 4 5% 33%	1630
May	1st to 10th	Night	20% 10% 3 5% 4 2 4 4 6% 7% 35%	1440
	11th to 20th	Night	19% 8% 3 6% 5% 3 4 4 5% 6% 37%	1415
	21st to end	Night	16% 8% 3 6% 6% 3 4 4 5% 6% 39%	1550
June	1st to 10th	Night	17% 8% 3 5% 7% 3 5% 5% 8% 9% 31%	1440
	11th to 20th	Night	16% 6% 3 6% 6% 3 5% 4 6% 8% 39%	1440
	21st to end	Night	18% 7% 3 5% 6% 4 4 4 6% 8% 35%	1440
July	1st to 10th	Night	12% 5% 3 6% 6% 3 6% 6% 7% 8% 39%	1440
	11th to 20th	Night	12% 5% 3 5% 5% 3 4 6% 6% 7% 43%	1440
	21st to end	Night	11% 5% 3 5% 6% 3 5% 6% 6% 8% 41%	1574
August	1st to 10th	Night	11% 6% 3 6% 6% 5% 5% 6% 6% 9% 38%	1432
	11th to 20th	Night	12% 6% 3 5% 5% 3 4 6% 7% 8% 42%	1572
	21st to end	Night	16% 5% 3 5% 4 3 3 5% 7% 9% 40%	1975
September	1st to 10th	Night	16% 6% 2 6% 5% 2 4 4 5% 5% 43%	1800
	11th to 20th	Night	18% 6% 2 5% 4 2 3 5% 4 7% 43%	1808
	21st to end	Night	20% 7% 2 5% 5% 3 4 4 4 6% 39%	2024
October	1st to 10th	Night	22% 9% 3 6% 5% 3 3 4 4 6% 37%	2160
	11th to 20th	Night	26% 12% 3 7% 6% 3 4 3 5% 6% 25%	2160
	21st to end	Night	26% 13% 4 7% 5% 3 5% 4 5% 5% 22%	2556
November	1st to 10th	Night	20% 14% 4 7% 5% 3 4 4 5% 5% 28%	2424
	11th to 20th	Night	20% 14% 5% 10% 8% 4 5% 4 4 5% 22%	2660
	21st to end	Night	23% 17% 7% 11% 7% 3 3 4 5% 4 16%	2660
December	1st to 10th	Night	21% 19% 9% 10% 7% 4 5% 4 3 4 13%	2660
	11th to 20th	Night	23% 17% 7% 9% 7% 3 3 4 4 5% 20%	3288
	21st to end	Night	22% 22% 6% 10% 7% 3 4 3 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	2270
	11th to 20th	Day	56% 2 7% 22% 11% 2	2134
	21st to end	Day	58% 2 8% 16% 13% 3	2344
May	1st to 10th	Day	55% 3 6% 21% 13% 2	2520
	11th to 20th	Day	53% 2 6% 21% 17% 2	2482
	21st to end	Day	51% 3 11% 19% 15% 2	2725
June	1st to 10th	Day	58% 3 8% 20% 10% 1	2520
	11th to 20th	Day	46% 3 10% 27% 12% 2	2520
	21st to end	Day	53% 4 12% 20% 10%	2520
July	1st to 10th	Day	44% 4 13% 28% 10% 1	2450
	11th to 20th	Day	47% 3 14% 27% 9%	2445
	21st to end	Day	49% 3 15% 26% 8%	2591
August	1st to 10th	Day	50% 6% 13% 24% 6%	2492
	11th to 20th	Day	47% 3 17% 25% 7%	2312
	21st to end	Day	48% 4 13% 25% 11%	2376
September	1st to 10th	Day	45% 2 14% 26% 13% 1	2160
	11th to 20th	Day	46% 3 13% 27% 10% 1	2152
	21st to end	Day	49% 3 13% 26% 8%	1935
October	1st to 10th	Day	55% 3 12% 21% 9%	1800
	11th to 20th	Day	66% 3 11% 16% 4 1	1800
	21st to end	Day	67% 3 10% 15% 5% 1	1800
November	1st to 10th	Day	55% 2 13% 22% 7% 1	1652
	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	50% 2 7% 25% 15% 2	1775
	21st to end	Night	56% 2 7% 18% 15% 3	1630
May	1st to 10th	Night	50% 2 7% 20% 18% 3	1440
	11th to 20th	Night	50% 3 6% 21% 16% 4	1416
	21st to end	Night	47% 3 11% 22% 15% 2	1551
June	1st to 10th	Night	49% 4 13% 23% 11% 1	1440
	11th to 20th	Night	46% 2 11% 25% 13% 3	1440
	21st to end	Night	48% 4 14% 22% 11% 1	1440
July	1st to 10th	Night	40% 4 16% 26% 13% 1	1400
	11th to 20th	Night	40% 3 14% 30% 11% 1	1392
	21st to end	Night	41% 4 19% 27% 9%	1486
August	1st to 10th	Night	43% 5% 17% 28% 8%	1422
	11th to 20th	Night	39% 4 20% 27% 10%	1572
	21st to end	Night	41% 4 17% 29% 9% 1	1975
September	1st to 10th	Night	43% 3 14% 28% 12% 1	1800
	11th to 20th	Night	41% 2 16% 31% 8%	1808
	21st to end	Night	47% 3 12% 30% 8%	2024
October	1st to 10th	Night	50% 2 11% 24% 11% 1	2160
	11th to 20th	Night	61% 3 11% 19% 5% 1	2160
	21st to end	Night	64% 3 10% 17% 6% 1	2556
November	1st to 10th	Night	60% 3 12% 18% 7%	2424
	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% 14% 28% 18% 7% 2	457
	11th to 20th	Day	34% 13% 24% 16% 12% 2	412
	21st to end	Day	31% 16% 29% 16% 7% 1	420
May	1st to 10th	Day	29% 13% 33% 18% 6% 2	423
	11th to 20th	Day	27% 13% 28% 21% 9% 2	447
	21st to end	Day	24% 15% 34% 18% 7% 2	485
June	1st to 10th	Day	28% 11% 33% 21% 6% 1	450
	11th to 20th	Day	23% 10% 35% 18% 13% 2	450
	21st to end	Day	25% 8% 28% 26% 12% 2	450
July	1st to 10th	Day	15% 7% 33% 32% 9% 3	445
	11th to 20th	Day	19% 9% 29% 29% 11% 2	444
	21st to end	Day	17% 6% 30% 32% 14% 2	488
August	1st to 10th	Day	21% 5% 27% 29% 14% 4	446
	11th to 20th	Day	19% 4 26% 27% 16% 7%	439
	21st to end	Day	20% 12% 28% 20% 14% 7%	495
September	1st to 10th	Day	22% 7% 28% 25% 11% 7%	450
	11th to 20th	Day	22% 10% 23% 23% 16% 5%	450
	21st to end	Day	24% 12% 24% 21% 13% 7%	450
October	1st to 10th	Day	28% 13% 25% 19% 12% 3	450
	11th to 20th	Day	36% 12% 28% 15% 7% 2	450
	21st to end	Day	37% 10% 27% 19% 6% 1	405
November	1st to 10th	Day	31% 13% 30% 19% 6%	346
	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% 12% 23% 27% 7%	760
	11th to 20th	Night	25% 12% 28% 24% 10% 1	711
	21st to end	Night	30% 10% 27% 23% 10% 1	550
May	1st to 10th	Night	25% 6% 30% 28% 10% 1	360
	11th to 20th	Night	24% 9% 26% 31% 10%	354
	21st to end	Night	21% 7% 33% 29% 9%	389
June	1st to 10th	Night	23% 5% 33% 31% 8%	360
	11th to 20th	Night	20% 6% 24% 35% 15%	360
	21st to end	Night	20% 5% 21% 38% 15% 1	360
July	1st to 10th	Night	13% 3 25% 42% 17%	350
	11th to 20th	Night	14% 3 22% 40% 20% 1	348
	21st to end	Night	12% 4 24% 42% 16% 2	394
August	1st to 10th	Night	15% 3 18% 40% 23% 1	358
	11th to 20th	Night	17% 3 18% 32% 27% 3	508
	21st to end	Night	20% 6% 22% 31% 19% 3	787
September	1st to 10th	Night	21% 4 24% 33% 17% 1	720
	11th to 20th	Night	23% 5% 21% 31% 19% 2	720
	21st to end	Night	25% 7% 24% 27% 16% 2	720
October	1st to 10th	Night	27% 9% 27% 25% 11% 1	720
	11th to 20th	Night	36% 9% 25% 21% 8% 1	720
	21st to end	Night	36% 10% 23% 25% 5% 1	792
November	1st to 10th	Night	31% 12% 26% 23% 7% 1	740
	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 2024-04-07 09:28:10. Version ac07

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