Ste-Agathe-des-Monts
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ste-Agathe-des-Monts clear sky chart from 2005-11-06 to 2025-07-21.

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% 6% 5% 5% 4 5% 6% 28%	120322
	Night	15% 12% 5% 10% 6% 5% 4 4 5% 6% 29%	118787
Transparency	Day	55% 5% 11% 19% 9% 1	123799
	Night	56% 5% 11% 18% 10% 1	123471
Seeing	Day	25% 19% 30% 17% 6% 2	15350
	Night	23% 17% 29% 23% 8% 1	24322

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% 9% 15% 5% 5% 6% 4 4 4 17%	3597
	11th to 20th	Day	10% 15% 7% 19% 11% 5% 4 2 3 5% 19%	3570
	21st to end	Day	7% 14% 8% 17% 6% 5% 5% 4 5% 5% 24%	3960
February	1st to 10th	Day	10% 19% 5% 12% 9% 5% 4 4 4 6% 22%	1768
	11th to 20th	Day	11% 18% 6% 12% 7% 6% 4 3 5% 5% 24%	1818
	21st to end	Day	14% 19% 5% 10% 7% 4 4 4 4 4 24%	1650
March	1st to 10th	Day	16% 17% 5% 13% 8% 4 4 3 4 4 22%	4476
	11th to 20th	Day	11% 15% 5% 11% 5% 5% 5% 3 5% 6% 28%	4766
	21st to end	Day	16% 13% 4 9% 5% 4 4 3 4 5% 32%	5919
April	1st to 10th	Day	19% 15% 4 9% 5% 3 3 3 4 6% 30%	2400
	11th to 20th	Day	21% 11% 4 8% 4 3 4 3 5% 5% 32%	2374
	21st to end	Day	21% 12% 4 9% 4 4 4 3 5% 5% 29%	2560
May	1st to 10th	Day	25% 12% 4 9% 5% 5% 5% 4 5% 6% 23%	6346
	11th to 20th	Day	20% 9% 3 7% 5% 5% 5% 5% 6% 7% 28%	6318
	21st to end	Day	23% 10% 3 7% 5% 5% 5% 3 4 7% 28%	6949
June	1st to 10th	Day	21% 9% 3 7% 5% 5% 5% 4 6% 7% 26%	2800
	11th to 20th	Day	15% 7% 3 8% 6% 6% 5% 4 7% 8% 31%	2800
	21st to end	Day	22% 10% 3 7% 5% 5% 6% 4 5% 6% 27%	2800
July	1st to 10th	Day	13% 7% 2 8% 7% 6% 7% 5% 7% 7% 30%	4580
	11th to 20th	Day	15% 6% 2 7% 5% 5% 6% 5% 7% 8% 34%	4580
	21st to end	Day	12% 6% 2 7% 4 5% 5% 4 6% 7% 43%	4814
August	1st to 10th	Day	15% 7% 3 8% 5% 6% 6% 5% 7% 8% 30%	4423
	11th to 20th	Day	16% 7% 3 7% 5% 4 5% 4 7% 8% 33%	4028
	21st to end	Day	16% 6% 3 6% 5% 5% 5% 4 6% 8% 36%	4180
September	1st to 10th	Day	15% 7% 2 7% 4 4 4 4 6% 7% 40%	2280
	11th to 20th	Day	15% 6% 3 6% 4 5% 4 3 6% 7% 43%	2223
	21st to end	Day	19% 9% 2 6% 4 4 3 3 5% 6% 38%	2090
October	1st to 10th	Day	22% 9% 3 6% 4 4 4 3 6% 6% 32%	1924
	11th to 20th	Day	22% 12% 3 8% 6% 5% 4 4 5% 5% 26%	1875
	21st to end	Day	24% 12% 4 9% 5% 4 5% 2 5% 5% 25%	1881
November	1st to 10th	Day	15% 13% 4 8% 5% 5% 5% 3 5% 6% 31%	1761
	11th to 20th	Day	18% 15% 5% 10% 7% 4 4 4 5% 6% 24%	1666
	21st to end	Day	20% 16% 7% 10% 6% 4 5% 4 5% 4 20%	1600
December	1st to 10th	Day	17% 17% 9% 15% 5% 5% 4 3 4 4 15%	2600
	11th to 20th	Day	15% 18% 7% 13% 5% 4 4 3 4 4 21%	2986
	21st to end	Day	18% 17% 7% 10% 5% 3 4 3 4 4 24%	3960
January	1st to 10th	Night	10% 21% 10% 15% 5% 4 4 4 4 4 18%	6349
	11th to 20th	Night	7% 14% 7% 20% 11% 6% 4 3 4 5% 19%	6315
	21st to end	Night	7% 12% 7% 18% 9% 6% 5% 4 5% 6% 22%	6996
February	1st to 10th	Night	11% 15% 6% 12% 8% 6% 5% 4 5% 6% 25%	2630
	11th to 20th	Night	10% 14% 6% 13% 7% 5% 5% 4 5% 5% 26%	2467
	21st to end	Night	11% 16% 6% 11% 4 5% 5% 3 6% 6% 26%	1980
March	1st to 10th	Night	18% 14% 5% 13% 6% 4 4 2 4 5% 26%	5364
	11th to 20th	Night	10% 14% 5% 10% 5% 5% 5% 4 6% 8% 28%	5191
	21st to end	Night	14% 11% 4 10% 6% 5% 5% 3 5% 6% 30%	5013
April	1st to 10th	Night	21% 12% 4 8% 5% 4 3 3 4 6% 30%	2000
	11th to 20th	Night	17% 9% 4 7% 5% 4 4 4 6% 5% 35%	1975
	21st to end	Night	20% 10% 3 8% 4 4 5% 3 4 5% 33%	1852
May	1st to 10th	Night	21% 11% 4 8% 5% 5% 5% 4 5% 6% 26%	3597
	11th to 20th	Night	20% 8% 3 7% 5% 4 4 3 5% 6% 34%	3575
	21st to end	Night	21% 9% 3 7% 5% 4 5% 4 6% 6% 28%	3926
June	1st to 10th	Night	18% 9% 2 7% 5% 4 5% 4 6% 8% 32%	1600
	11th to 20th	Night	18% 7% 2 7% 5% 3 4 4 4 8% 37%	1600
	21st to end	Night	21% 6% 3 6% 4 5% 5% 4 5% 6% 35%	1600
July	1st to 10th	Night	13% 8% 2 8% 6% 6% 6% 5% 5% 7% 35%	2600
	11th to 20th	Night	15% 6% 2 7% 4 3 5% 4 5% 8% 41%	2600
	21st to end	Night	11% 6% 2 5% 4 5% 4 4 6% 8% 47%	2739
August	1st to 10th	Night	12% 6% 3 8% 5% 4 4 4 6% 8% 39%	2506
	11th to 20th	Night	15% 8% 3 7% 4 4 4 3 5% 6% 41%	2766
	21st to end	Night	18% 5% 2 6% 4 4 4 3 5% 7% 42%	3476
September	1st to 10th	Night	12% 8% 3 6% 3 4 4 4 6% 6% 46%	1900
	11th to 20th	Night	15% 5% 2 5% 3 3 3 4 5% 7% 48%	1957
	21st to end	Night	18% 6% 2 5% 4 3 3 4 5% 7% 43%	2090
October	1st to 10th	Night	16% 9% 3 7% 5% 5% 4 3 4 6% 37%	2251
	11th to 20th	Night	20% 11% 3 8% 4 5% 4 4 4 6% 32%	2304
	21st to end	Night	23% 10% 3 8% 5% 4 4 3 5% 7% 27%	2717
November	1st to 10th	Night	17% 10% 5% 9% 5% 5% 5% 3 6% 6% 28%	2537
	11th to 20th	Night	15% 13% 4 10% 6% 5% 5% 4 5% 7% 27%	2730
	21st to end	Night	18% 17% 5% 11% 6% 5% 4 4 4 5% 23%	2800
December	1st to 10th	Night	15% 15% 6% 12% 7% 6% 5% 5% 6% 6% 17%	4580
	11th to 20th	Night	21% 13% 6% 12% 6% 5% 4 3 3 4 24%	5208
	21st to end	Night	19% 20% 5% 10% 5% 3 3 2 3 4 26%	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	70% 6% 6% 14% 4	3598
	11th to 20th	Day	69% 3 5% 13% 8% 2	3600
	21st to end	Day	62% 5% 7% 13% 12% 1	3960
February	1st to 10th	Day	63% 3 7% 16% 8% 2	1768
	11th to 20th	Day	63% 4 8% 14% 10% 1	1827
	21st to end	Day	63% 3 7% 14% 10% 2	1650
March	1st to 10th	Day	66% 3 6% 10% 12% 3	4479
	11th to 20th	Day	57% 4 14% 12% 11% 2	4766
	21st to end	Day	55% 3 6% 16% 18% 2	5919
April	1st to 10th	Day	57% 4 8% 17% 12% 3	2400
	11th to 20th	Day	54% 5% 8% 19% 12% 2	2374
	21st to end	Day	57% 4 7% 16% 12% 3	2560
May	1st to 10th	Day	62% 5% 7% 18% 8% 1	6357
	11th to 20th	Day	54% 5% 14% 17% 8% 2	6322
	21st to end	Day	57% 4 10% 17% 12% 1	6949
June	1st to 10th	Day	56% 6% 9% 18% 11% 1	2800
	11th to 20th	Day	48% 6% 13% 20% 11% 3	2800
	21st to end	Day	57% 6% 10% 18% 8% 1	2800
July	1st to 10th	Day	49% 5% 14% 23% 8%	4510
	11th to 20th	Day	45% 6% 17% 27% 6%	4505
	21st to end	Day	40% 5% 15% 31% 9%	4661
August	1st to 10th	Day	50% 6% 16% 22% 6%	4409
	11th to 20th	Day	45% 7% 17% 26% 5%	4070
	21st to end	Day	45% 5% 15% 21% 13% 1	4180
September	1st to 10th	Day	44% 5% 13% 26% 12%	2280
	11th to 20th	Day	40% 6% 13% 29% 11% 1	2223
	21st to end	Day	47% 4 13% 25% 11%	2090
October	1st to 10th	Day	48% 4 13% 27% 8%	3197
	11th to 20th	Day	50% 5% 13% 23% 7%	3091
	21st to end	Day	52% 4 20% 15% 9% 1	3081
November	1st to 10th	Day	53% 5% 13% 19% 8% 1	1761
	11th to 20th	Day	61% 6% 10% 12% 10% 1	1666
	21st to end	Day	66% 7% 10% 12% 4 1	1600
December	1st to 10th	Day	73% 4 8% 11% 3	2600
	11th to 20th	Day	66% 4 7% 15% 8%	2986
	21st to end	Day	63% 5% 6% 15% 10%	3960
January	1st to 10th	Night	69% 4 10% 13% 4	6349
	11th to 20th	Night	68% 4 10% 13% 5% 1	6360
	21st to end	Night	64% 4 7% 10% 14% 1	6996
February	1st to 10th	Night	60% 5% 8% 17% 8% 1	2630
	11th to 20th	Night	60% 5% 9% 17% 9% 1	2469
	21st to end	Night	57% 4 9% 17% 11% 2	1980
March	1st to 10th	Night	62% 3 8% 11% 13% 3	5374
	11th to 20th	Night	54% 6% 11% 16% 10% 3	5192
	21st to end	Night	56% 4 6% 20% 12% 3	5013
April	1st to 10th	Night	56% 3 7% 19% 13% 2	2000
	11th to 20th	Night	50% 5% 9% 21% 14% 2	1975
	21st to end	Night	52% 5% 8% 19% 13% 3	1852
May	1st to 10th	Night	58% 5% 11% 18% 7% 2	3603
	11th to 20th	Night	50% 7% 14% 18% 10% 2	3576
	21st to end	Night	56% 4 10% 17% 11% 1	3927
June	1st to 10th	Night	49% 6% 11% 21% 12%	1600
	11th to 20th	Night	46% 5% 11% 22% 13% 3	1600
	21st to end	Night	50% 6% 12% 20% 12% 1	1600
July	1st to 10th	Night	48% 5% 18% 20% 9%	2560
	11th to 20th	Night	42% 5% 19% 29% 5%	2552
	21st to end	Night	35% 6% 20% 27% 12%	2651
August	1st to 10th	Night	42% 7% 16% 28% 7%	2496
	11th to 20th	Night	44% 5% 19% 25% 7%	2790
	21st to end	Night	43% 4 16% 24% 11% 2	3476
September	1st to 10th	Night	38% 6% 14% 28% 13% 1	1900
	11th to 20th	Night	35% 6% 16% 32% 11% 1	1957
	21st to end	Night	41% 6% 13% 28% 12%	2090
October	1st to 10th	Night	46% 4 13% 24% 11% 1	3758
	11th to 20th	Night	47% 5% 13% 25% 9%	3827
	21st to end	Night	50% 5% 18% 16% 10% 1	4467
November	1st to 10th	Night	55% 6% 13% 19% 6% 1	2537
	11th to 20th	Night	58% 5% 10% 16% 8% 2	2730
	21st to end	Night	64% 6% 9% 14% 6% 1	2800
December	1st to 10th	Night	67% 4 13% 12% 4	4580
	11th to 20th	Night	66% 4 4 15% 10% 1	5208
	21st to end	Night	65% 3 5% 12% 14% 1	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	20% 26% 40% 12% 3	200
	11th to 20th	Day	29% 22% 34% 12% 5% 1	200
	21st to end	Day	22% 24% 36% 13% 4	220
February	1st to 10th	Day	34% 31% 28% 6% 1	285
	11th to 20th	Day	27% 31% 35% 7% 1	365
	21st to end	Day	30% 24% 33% 12% 1	414
March	1st to 10th	Day	27% 23% 34% 13% 2	500
	11th to 20th	Day	27% 27% 30% 13% 3 1	500
	21st to end	Day	31% 24% 25% 14% 5% 1	550
April	1st to 10th	Day	34% 20% 29% 12% 4 1	500
	11th to 20th	Day	36% 20% 24% 12% 8% 1	492
	21st to end	Day	32% 20% 32% 11% 4 1	500
May	1st to 10th	Day	28% 23% 31% 14% 4 1	503
	11th to 20th	Day	25% 19% 31% 17% 6% 1	527
	21st to end	Day	27% 19% 30% 19% 4	573
June	1st to 10th	Day	26% 17% 35% 16% 6%	530
	11th to 20th	Day	18% 22% 33% 17% 9% 1	530
	21st to end	Day	28% 16% 33% 16% 5% 1	530
July	1st to 10th	Day	17% 14% 36% 24% 8% 2	525
	11th to 20th	Day	16% 14% 37% 27% 5% 1	524
	21st to end	Day	14% 13% 36% 27% 7% 2	532
August	1st to 10th	Day	18% 11% 29% 29% 11% 2	486
	11th to 20th	Day	16% 9% 30% 27% 13% 5%	479
	21st to end	Day	16% 19% 28% 21% 10% 6%	539
September	1st to 10th	Day	20% 14% 30% 22% 10% 4	490
	11th to 20th	Day	14% 14% 27% 22% 14% 8%	490
	21st to end	Day	23% 16% 23% 22% 11% 5%	490
October	1st to 10th	Day	28% 18% 24% 18% 10% 2	490
	11th to 20th	Day	30% 22% 26% 16% 6% 1	476
	21st to end	Day	35% 15% 30% 16% 4	429
November	1st to 10th	Day	33% 19% 28% 16% 3 1	395
	11th to 20th	Day	28% 27% 27% 12% 5%	266
	21st to end	Day	32% 27% 31% 10% 2	200
December	1st to 10th	Day	31% 22% 28% 13% 6%	200
	11th to 20th	Day	31% 28% 31% 8% 2 1	200
	21st to end	Day	33% 25% 26% 11% 3 2	220
January	1st to 10th	Night	23% 22% 36% 15% 4	800
	11th to 20th	Night	24% 25% 28% 18% 5%	800
	21st to end	Night	15% 20% 38% 20% 5% 1	880
February	1st to 10th	Night	19% 25% 33% 19% 3 1	800
	11th to 20th	Night	22% 24% 36% 15% 3	783
	21st to end	Night	23% 20% 34% 21% 3	660
March	1st to 10th	Night	24% 22% 33% 18% 3	800
	11th to 20th	Night	23% 24% 30% 19% 4 1	800
	21st to end	Night	24% 19% 29% 22% 5% 1	880
April	1st to 10th	Night	28% 19% 27% 22% 4	800
	11th to 20th	Night	24% 20% 29% 22% 5% 1	791
	21st to end	Night	27% 18% 29% 19% 7%	652
May	1st to 10th	Night	26% 12% 32% 23% 5% 2	403
	11th to 20th	Night	21% 12% 29% 27% 9% 1	394
	21st to end	Night	21% 11% 37% 24% 7%	433
June	1st to 10th	Night	23% 10% 31% 29% 8%	400
	11th to 20th	Night	22% 9% 24% 32% 12% 1	400
	21st to end	Night	23% 7% 24% 33% 13% 1	400
July	1st to 10th	Night	14% 8% 28% 36% 13% 1	390
	11th to 20th	Night	14% 7% 23% 40% 15% 1	388
	21st to end	Night	13% 7% 25% 40% 14% 1	416
August	1st to 10th	Night	13% 7% 20% 43% 15% 1	378
	11th to 20th	Night	14% 6% 23% 32% 24% 1	542
	21st to end	Night	17% 8% 26% 31% 15% 2	836
September	1st to 10th	Night	16% 9% 30% 31% 13% 1	760
	11th to 20th	Night	17% 10% 22% 31% 20% 2	760
	21st to end	Night	21% 12% 24% 25% 16% 2	760
October	1st to 10th	Night	23% 13% 27% 24% 13% 1	760
	11th to 20th	Night	27% 14% 29% 22% 7% 1	760
	21st to end	Night	29% 17% 27% 23% 5%	836
November	1st to 10th	Night	26% 20% 26% 22% 5% 1	780
	11th to 20th	Night	25% 21% 28% 17% 8% 1	800
	21st to end	Night	29% 24% 24% 17% 5% 1	800
December	1st to 10th	Night	29% 21% 28% 16% 6% 1	800
	11th to 20th	Night	29% 24% 25% 16% 5% 1	800
	21st to end	Night	32% 21% 26% 16% 4	880

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