Montmagny
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Montmagny clear sky chart from 2005-11-06 to 2026-07-01.

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% 32%	137624
	Night	16% 12% 4 10% 6% 5% 5% 4 5% 6% 28%	134785
Transparency	Day	50% 7% 13% 20% 9% 1	141066
	Night	55% 7% 12% 18% 8% 1	139434
Seeing	Day	23% 17% 30% 21% 8% 1	17549
	Night	24% 13% 31% 24% 7% 1	25902

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% 18% 5% 11% 5% 4 4 3 5% 6% 27%	4605
	11th to 20th	Day	10% 14% 6% 13% 8% 6% 5% 4 5% 6% 23%	4650
	21st to end	Day	5% 8% 5% 12% 7% 6% 5% 4 6% 8% 35%	5124
February	1st to 10th	Day	10% 11% 5% 10% 7% 6% 6% 4 6% 7% 28%	1713
	11th to 20th	Day	12% 13% 5% 12% 6% 5% 4 4 5% 5% 29%	1991
	21st to end	Day	12% 12% 5% 9% 7% 5% 5% 4 5% 6% 31%	1730
March	1st to 10th	Day	18% 14% 4 10% 6% 5% 5% 3 5% 6% 25%	4576
	11th to 20th	Day	13% 13% 4 8% 5% 6% 5% 4 6% 7% 28%	4934
	21st to end	Day	15% 14% 4 9% 5% 4 3 3 4 6% 32%	5852
April	1st to 10th	Day	20% 11% 4 9% 5% 4 3 3 5% 5% 30%	2520
	11th to 20th	Day	19% 9% 3 6% 4 3 4 3 4 6% 38%	2631
	21st to end	Day	21% 8% 3 7% 5% 4 4 4 5% 6% 34%	2730
May	1st to 10th	Day	20% 9% 3 8% 5% 5% 4 3 5% 7% 30%	7698
	11th to 20th	Day	19% 8% 3 7% 5% 5% 5% 4 5% 7% 33%	8221
	21st to end	Day	18% 8% 3 8% 5% 5% 6% 4 7% 7% 29%	9419
June	1st to 10th	Day	17% 7% 2 7% 5% 5% 5% 6% 7% 8% 30%	3150
	11th to 20th	Day	17% 7% 3 7% 4 5% 5% 4 7% 8% 36%	3150
	21st to end	Day	18% 8% 3 7% 6% 5% 4 4 7% 8% 29%	3150
July	1st to 10th	Day	16% 7% 3 8% 5% 6% 5% 4 7% 8% 30%	6682
	11th to 20th	Day	13% 5% 3 7% 5% 5% 6% 4 7% 9% 37%	6360
	21st to end	Day	11% 5% 2 6% 4 4 5% 4 6% 9% 43%	6926
August	1st to 10th	Day	13% 6% 2 7% 5% 5% 6% 5% 8% 10% 34%	4481
	11th to 20th	Day	16% 7% 3 8% 6% 5% 6% 4 6% 8% 32%	4175
	21st to end	Day	17% 7% 2 6% 3 4 4 4 6% 7% 41%	4553
September	1st to 10th	Day	14% 5% 2 5% 5% 5% 5% 3 6% 9% 41%	2395
	11th to 20th	Day	15% 5% 2 6% 4 3 3 2 5% 6% 49%	2200
	21st to end	Day	18% 6% 3 6% 3 4 4 3 5% 7% 41%	2200
October	1st to 10th	Day	16% 8% 3 7% 4 3 4 4 5% 8% 38%	2197
	11th to 20th	Day	20% 10% 3 8% 6% 5% 5% 4 6% 6% 27%	1835
	21st to end	Day	25% 11% 3 8% 5% 4 4 3 5% 6% 26%	1980
November	1st to 10th	Day	16% 11% 4 8% 5% 5% 5% 4 5% 6% 29%	1851
	11th to 20th	Day	18% 13% 4 11% 6% 4 4 4 5% 5% 27%	1847
	21st to end	Day	18% 17% 5% 10% 6% 4 4 3 6% 5% 21%	1507
December	1st to 10th	Day	17% 14% 6% 11% 6% 6% 5% 3 5% 6% 22%	2350
	11th to 20th	Day	18% 10% 4 11% 6% 5% 5% 3 5% 6% 25%	2688
	21st to end	Day	18% 13% 5% 11% 5% 5% 5% 4 7% 6% 22%	3553
January	1st to 10th	Night	14% 15% 5% 13% 7% 5% 5% 4 4 5% 22%	8275
	11th to 20th	Night	10% 19% 7% 17% 7% 6% 5% 4 5% 5% 17%	8235
	21st to end	Night	5% 9% 6% 15% 8% 6% 6% 5% 6% 6% 28%	9057
February	1st to 10th	Night	9% 14% 5% 11% 6% 5% 5% 5% 5% 7% 29%	2905
	11th to 20th	Night	11% 15% 5% 11% 7% 5% 4 4 6% 5% 27%	2512
	21st to end	Night	13% 15% 5% 11% 5% 4 4 3 4 7% 30%	2076
March	1st to 10th	Night	19% 13% 5% 11% 6% 4 5% 3 4 5% 25%	5484
	11th to 20th	Night	13% 15% 4 10% 7% 7% 6% 5% 5% 6% 22%	5244
	21st to end	Night	18% 15% 5% 9% 4 4 4 3 4 5% 29%	5318
April	1st to 10th	Night	22% 14% 4 8% 4 4 3 3 4 5% 29%	2100
	11th to 20th	Night	20% 8% 3 8% 4 5% 4 4 5% 8% 32%	1936
	21st to end	Night	23% 10% 3 6% 5% 4 3 3 3 5% 34%	1890
May	1st to 10th	Night	23% 9% 3 7% 4 4 4 4 5% 6% 30%	5241
	11th to 20th	Night	22% 8% 2 7% 5% 5% 5% 3 5% 6% 30%	4639
	21st to end	Night	18% 7% 3 7% 4 5% 5% 4 6% 7% 36%	4756
June	1st to 10th	Night	19% 9% 2 7% 5% 6% 6% 5% 5% 8% 29%	1470
	11th to 20th	Night	16% 8% 4 6% 4 4 4 4 6% 8% 37%	1470
	21st to end	Night	21% 8% 3 8% 5% 5% 5% 3 5% 7% 30%	1470
July	1st to 10th	Night	12% 7% 3 8% 5% 6% 5% 5% 7% 9% 33%	3287
	11th to 20th	Night	19% 6% 2 7% 4 5% 5% 4 6% 8% 34%	3600
	21st to end	Night	11% 6% 3 8% 5% 6% 4 4 5% 8% 40%	3926
August	1st to 10th	Night	17% 7% 3 7% 5% 4 4 3 5% 7% 36%	2636
	11th to 20th	Night	16% 7% 3 9% 6% 6% 5% 4 7% 8% 29%	2872
	21st to end	Night	15% 8% 3 8% 6% 5% 5% 4 5% 6% 36%	3343
September	1st to 10th	Night	16% 7% 2 7% 4 4 4 4 5% 7% 40%	2005
	11th to 20th	Night	16% 8% 2 5% 4 3 4 4 4 6% 44%	2200
	21st to end	Night	18% 7% 3 7% 4 3 4 4 5% 6% 40%	2200
October	1st to 10th	Night	17% 9% 3 7% 4 3 4 4 5% 7% 38%	2202
	11th to 20th	Night	24% 9% 3 8% 4 4 4 3 4 6% 30%	2561
	21st to end	Night	23% 10% 3 8% 4 4 5% 3 5% 7% 28%	2860
November	1st to 10th	Night	18% 13% 3 8% 5% 5% 4 3 5% 6% 29%	2667
	11th to 20th	Night	18% 12% 4 10% 5% 5% 5% 3 5% 6% 29%	2772
	21st to end	Night	19% 18% 4 10% 5% 4 4 4 4 5% 23%	3108
December	1st to 10th	Night	15% 15% 7% 12% 9% 6% 5% 4 5% 5% 18%	5060
	11th to 20th	Night	19% 13% 5% 10% 7% 5% 5% 3 5% 5% 23%	5741
	21st to end	Night	17% 17% 4 10% 6% 4 4 3 4 4 25%	7667

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% 7% 10% 18% 8%	4606
	11th to 20th	Day	59% 10% 9% 16% 5% 1	4680
	21st to end	Day	46% 7% 11% 22% 14%	5124
February	1st to 10th	Day	55% 6% 10% 18% 9% 1	1713
	11th to 20th	Day	58% 5% 10% 17% 9% 1	2000
	21st to end	Day	54% 6% 8% 20% 10% 2	1730
March	1st to 10th	Day	60% 6% 9% 12% 10% 3	4579
	11th to 20th	Day	53% 7% 17% 16% 7% 1	4934
	21st to end	Day	55% 5% 7% 18% 12% 3	5852
April	1st to 10th	Day	57% 5% 10% 16% 11% 2	2520
	11th to 20th	Day	49% 6% 9% 22% 12% 2	2631
	21st to end	Day	52% 6% 10% 18% 12% 2	2730
May	1st to 10th	Day	53% 6% 11% 18% 11% 1	7710
	11th to 20th	Day	50% 8% 13% 21% 6% 2	8225
	21st to end	Day	50% 9% 12% 17% 11% 1	9420
June	1st to 10th	Day	49% 9% 13% 21% 8% 1	3150
	11th to 20th	Day	46% 8% 13% 23% 10% 1	3150
	21st to end	Day	53% 8% 12% 18% 9%	3150
July	1st to 10th	Day	49% 8% 13% 22% 7%	6610
	11th to 20th	Day	41% 9% 20% 25% 5%	6285
	21st to end	Day	37% 8% 19% 27% 8%	6728
August	1st to 10th	Day	43% 11% 20% 21% 6%	4467
	11th to 20th	Day	47% 11% 19% 18% 5%	4214
	21st to end	Day	43% 9% 17% 19% 12%	4553
September	1st to 10th	Day	41% 7% 14% 27% 11% 1	2395
	11th to 20th	Day	38% 5% 15% 30% 12% 1	2200
	21st to end	Day	44% 6% 13% 26% 12%	2200
October	1st to 10th	Day	49% 7% 12% 27% 6%	3574
	11th to 20th	Day	52% 6% 17% 23% 2	2960
	21st to end	Day	51% 6% 16% 20% 7%	3180
November	1st to 10th	Day	56% 7% 13% 18% 7%	1851
	11th to 20th	Day	60% 6% 9% 19% 6%	1847
	21st to end	Day	64% 7% 12% 13% 3	1507
December	1st to 10th	Day	61% 8% 12% 11% 9%	2350
	11th to 20th	Day	59% 7% 10% 18% 7%	2688
	21st to end	Day	59% 8% 12% 12% 8% 1	3553
January	1st to 10th	Night	63% 7% 10% 14% 6%	8275
	11th to 20th	Night	69% 7% 8% 12% 4	8280
	21st to end	Night	52% 8% 10% 16% 13%	9057
February	1st to 10th	Night	55% 6% 10% 18% 10% 1	2905
	11th to 20th	Night	59% 6% 10% 14% 11% 1	2514
	21st to end	Night	56% 5% 8% 18% 12% 1	2076
March	1st to 10th	Night	62% 5% 8% 12% 12% 1	5494
	11th to 20th	Night	59% 9% 12% 11% 7% 1	5245
	21st to end	Night	59% 3 6% 20% 10% 1	5318
April	1st to 10th	Night	59% 4 7% 14% 13% 3	2100
	11th to 20th	Night	51% 6% 9% 21% 12% 1	1936
	21st to end	Night	54% 5% 8% 18% 13% 2	1890
May	1st to 10th	Night	53% 6% 11% 18% 11% 1	5247
	11th to 20th	Night	53% 7% 10% 20% 9%	4640
	21st to end	Night	46% 7% 13% 18% 14% 2	4757
June	1st to 10th	Night	54% 8% 11% 20% 7%	1470
	11th to 20th	Night	46% 8% 12% 21% 10% 3	1470
	21st to end	Night	54% 8% 12% 16% 10%	1470
July	1st to 10th	Night	46% 8% 20% 21% 5%	3250
	11th to 20th	Night	46% 9% 19% 23% 3	3552
	21st to end	Night	40% 8% 21% 22% 8%	3809
August	1st to 10th	Night	48% 7% 16% 24% 5%	2626
	11th to 20th	Night	50% 11% 17% 17% 5%	2899
	21st to end	Night	47% 8% 13% 21% 12%	3343
September	1st to 10th	Night	43% 7% 13% 24% 11% 1	2005
	11th to 20th	Night	42% 6% 17% 26% 9%	2200
	21st to end	Night	46% 6% 11% 25% 12%	2200
October	1st to 10th	Night	47% 6% 13% 27% 6%	3605
	11th to 20th	Night	53% 6% 13% 24% 3	4175
	21st to end	Night	50% 6% 18% 17% 8%	4610
November	1st to 10th	Night	57% 7% 12% 18% 6%	2667
	11th to 20th	Night	57% 6% 12% 17% 7%	2772
	21st to end	Night	64% 6% 11% 13% 5% 1	3108
December	1st to 10th	Night	66% 8% 12% 11% 3	5060
	11th to 20th	Night	62% 6% 8% 17% 6%	5742
	21st to end	Night	63% 5% 10% 15% 7% 1	7667

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	25% 30% 27% 14% 4	220
	11th to 20th	Day	32% 23% 28% 13% 3 1	220
	21st to end	Day	15% 31% 34% 14% 5%	242
February	1st to 10th	Day	22% 23% 35% 15% 4 1	253
	11th to 20th	Day	22% 27% 34% 15% 3	506
	21st to end	Day	23% 22% 32% 20% 3	446
March	1st to 10th	Day	26% 25% 26% 18% 4 1	540
	11th to 20th	Day	26% 18% 31% 19% 6% 1	540
	21st to end	Day	24% 20% 29% 17% 7% 2	594
April	1st to 10th	Day	31% 19% 30% 14% 6% 1	540
	11th to 20th	Day	30% 18% 27% 18% 5% 1	532
	21st to end	Day	25% 20% 31% 17% 6% 2	540
May	1st to 10th	Day	28% 15% 34% 17% 5% 1	543
	11th to 20th	Day	23% 14% 29% 25% 8% 1	567
	21st to end	Day	22% 18% 35% 18% 6%	742
June	1st to 10th	Day	21% 13% 32% 25% 8% 1	780
	11th to 20th	Day	21% 13% 30% 24% 11% 1	780
	21st to end	Day	23% 9% 31% 25% 11% 1	780
July	1st to 10th	Day	17% 13% 30% 28% 10% 1	663
	11th to 20th	Day	16% 14% 33% 26% 9% 2	524
	21st to end	Day	16% 10% 34% 28% 11% 1	576
August	1st to 10th	Day	15% 12% 32% 25% 14% 3	526
	11th to 20th	Day	16% 8% 28% 30% 16% 2	519
	21st to end	Day	19% 14% 24% 24% 13% 5%	583
September	1st to 10th	Day	19% 12% 28% 26% 11% 3	530
	11th to 20th	Day	19% 10% 29% 26% 12% 3	530
	21st to end	Day	20% 13% 28% 24% 10% 5%	530
October	1st to 10th	Day	21% 17% 32% 19% 9% 2	527
	11th to 20th	Day	28% 15% 29% 18% 9% 1	420
	21st to end	Day	32% 20% 29% 13% 5%	462
November	1st to 10th	Day	30% 20% 32% 16% 3	425
	11th to 20th	Day	27% 20% 29% 17% 7%	430
	21st to end	Day	29% 23% 32% 15% 1	257
December	1st to 10th	Day	28% 18% 31% 18% 4 1	220
	11th to 20th	Day	33% 25% 26% 10% 3 1	220
	21st to end	Day	34% 20% 30% 14% 2	242
January	1st to 10th	Night	27% 18% 33% 18% 4	848
	11th to 20th	Night	24% 20% 33% 20% 4	840
	21st to end	Night	17% 18% 36% 23% 5%	924
February	1st to 10th	Night	17% 17% 36% 23% 6%	840
	11th to 20th	Night	23% 18% 39% 15% 5%	823
	21st to end	Night	24% 14% 33% 24% 4	692
March	1st to 10th	Night	24% 15% 36% 21% 4	840
	11th to 20th	Night	23% 14% 35% 22% 5% 1	840
	21st to end	Night	24% 14% 32% 24% 7% 1	924
April	1st to 10th	Night	31% 14% 27% 22% 6%	840
	11th to 20th	Night	27% 12% 32% 23% 6% 1	692
	21st to end	Night	29% 11% 27% 24% 8%	630
May	1st to 10th	Night	28% 11% 30% 24% 8%	625
	11th to 20th	Night	25% 6% 29% 30% 9% 1	414
	21st to end	Night	26% 8% 34% 26% 6%	455
June	1st to 10th	Night	24% 6% 30% 34% 7%	420
	11th to 20th	Night	18% 5% 27% 36% 14%	420
	21st to end	Night	24% 7% 30% 30% 9%	420
July	1st to 10th	Night	20% 6% 33% 31% 10%	390
	11th to 20th	Night	18% 6% 29% 33% 13% 1	388
	21st to end	Night	14% 5% 32% 38% 11% 1	438
August	1st to 10th	Night	16% 5% 25% 38% 15% 1	422
	11th to 20th	Night	17% 7% 24% 37% 14% 1	592
	21st to end	Night	16% 7% 31% 31% 12% 2	728
September	1st to 10th	Night	21% 7% 28% 32% 11% 1	800
	11th to 20th	Night	20% 8% 29% 31% 11% 1	800
	21st to end	Night	22% 10% 28% 29% 12% 1	800
October	1st to 10th	Night	23% 12% 32% 25% 7% 1	800
	11th to 20th	Night	31% 11% 28% 23% 8% 1	800
	21st to end	Night	28% 16% 32% 20% 5%	880
November	1st to 10th	Night	29% 17% 28% 21% 4	820
	11th to 20th	Night	28% 17% 27% 21% 6% 1	862
	21st to end	Night	29% 16% 31% 18% 4 1	950
December	1st to 10th	Night	30% 16% 32% 18% 4	950
	11th to 20th	Night	28% 21% 31% 15% 5% 1	950
	21st to end	Night	31% 19% 29% 18% 3 1	1045

Page generated at 2026-06-28 02:10:47. Version ac07

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