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 2024-02-10.

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	16% 9% 4 7% 6% 4 5% 5% 6% 7% 32%	77853
	Night	17% 11% 4 8% 6% 3 5% 5% 5% 6% 29%	81109
Transparency	Day	51% 7% 12% 20% 9% 1	77556
	Night	56% 7% 11% 17% 9% 1	80942
Seeing	Day	24% 15% 30% 21% 8% 2	14352
	Night	25% 12% 31% 24% 7% 1	22913

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	11% 16% 6% 10% 8% 4 6% 5% 6% 7% 21%	2486
	11th to 20th	Day	12% 11% 5% 9% 8% 4 5% 5% 5% 7% 28%	2520
	21st to end	Day	9% 8% 5% 9% 8% 5% 5% 6% 5% 8% 32%	2772
February	1st to 10th	Day	11% 11% 5% 9% 7% 4 7% 4 7% 7% 27%	1540
	11th to 20th	Day	13% 13% 5% 11% 7% 4 5% 5% 5% 6% 27%	1699
	21st to end	Day	13% 12% 4 9% 7% 3 6% 4 5% 6% 31%	1480
March	1st to 10th	Day	13% 12% 4 8% 5% 4 5% 5% 6% 7% 31%	1797
	11th to 20th	Day	15% 10% 4 8% 8% 4 5% 4 5% 6% 31%	1912
	21st to end	Day	15% 10% 4 7% 6% 4 4 5% 4 6% 34%	2272
April	1st to 10th	Day	21% 10% 4 9% 6% 3 4 4 5% 6% 29%	2160
	11th to 20th	Day	19% 8% 2 5% 4 3 3 4 4 5% 41%	2250
	21st to end	Day	22% 8% 3 6% 6% 3 4 4 5% 6% 32%	2340
May	1st to 10th	Day	19% 7% 3 6% 6% 3 4 5% 4 8% 36%	2358
	11th to 20th	Day	17% 7% 3 5% 5% 4 6% 5% 5% 7% 36%	2478
	21st to end	Day	18% 6% 3 6% 6% 3 5% 4 6% 8% 34%	2832
June	1st to 10th	Day	18% 6% 2 6% 6% 3 6% 7% 7% 9% 30%	2700
	11th to 20th	Day	17% 6% 3 5% 5% 3 6% 5% 6% 8% 35%	2700
	21st to end	Day	18% 8% 4 7% 6% 4 5% 5% 7% 9% 29%	2700
July	1st to 10th	Day	12% 5% 3 7% 6% 4 6% 6% 7% 10% 35%	2646
	11th to 20th	Day	13% 5% 3 6% 6% 4 5% 5% 7% 10% 36%	2520
	21st to end	Day	14% 7% 3 6% 5% 4 5% 5% 7% 9% 36%	2744
August	1st to 10th	Day	14% 6% 3 5% 5% 4 7% 7% 7% 11% 31%	2467
	11th to 20th	Day	12% 6% 3 5% 6% 3 5% 5% 6% 9% 40%	2304
	21st to end	Day	13% 6% 2 5% 5% 3 5% 6% 7% 8% 40%	2512
September	1st to 10th	Day	16% 5% 2 5% 5% 4 5% 4 6% 9% 40%	2156
	11th to 20th	Day	17% 5% 2 5% 5% 2 2 3 4 6% 48%	1980
	21st to end	Day	19% 6% 3 5% 4 3 4 4 5% 7% 41%	1980
October	1st to 10th	Day	16% 7% 4 6% 5% 2 5% 5% 5% 8% 37%	1978
	11th to 20th	Day	21% 10% 4 7% 7% 4 5% 5% 6% 6% 26%	1652
	21st to end	Day	26% 10% 4 7% 6% 4 3 4 5% 6% 24%	1782
November	1st to 10th	Day	16% 10% 4 7% 6% 5% 5% 5% 5% 7% 30%	1671
	11th to 20th	Day	19% 11% 4 9% 7% 4 4 5% 5% 5% 26%	1672
	21st to end	Day	19% 15% 5% 9% 7% 3 4 4 6% 5% 23%	1364
December	1st to 10th	Day	21% 15% 6% 10% 7% 4 5% 3 4 5% 19%	1330
	11th to 20th	Day	20% 12% 4 9% 7% 4 6% 4 5% 6% 25%	1668
	21st to end	Day	21% 13% 4 8% 6% 3 4 4 5% 6% 24%	2431
January	1st to 10th	Night	13% 16% 6% 12% 9% 4 4 5% 4 5% 20%	4457
	11th to 20th	Night	12% 14% 5% 11% 8% 4 6% 6% 5% 6% 23%	4440
	21st to end	Night	10% 11% 5% 9% 9% 4 6% 6% 7% 7% 26%	4884
February	1st to 10th	Night	10% 13% 6% 9% 7% 5% 5% 6% 5% 7% 27%	2623
	11th to 20th	Night	13% 15% 6% 10% 8% 4 5% 4 5% 5% 26%	2145
	21st to end	Night	14% 13% 6% 10% 7% 3 5% 4 4 7% 28%	1776
March	1st to 10th	Night	14% 14% 5% 8% 6% 4 4 4 5% 7% 29%	2150
	11th to 20th	Night	15% 11% 4 8% 7% 4 5% 5% 5% 6% 30%	2046
	21st to end	Night	16% 13% 4 7% 5% 3 4 4 5% 6% 31%	2080
April	1st to 10th	Night	23% 13% 4 7% 5% 3 4 4 4 6% 28%	1800
	11th to 20th	Night	19% 7% 3 7% 5% 4 4 5% 5% 8% 34%	1657
	21st to end	Night	24% 10% 4 6% 5% 3 4 4 3 5% 33%	1620
May	1st to 10th	Night	24% 9% 3 6% 5% 2 5% 4 4 6% 32%	1616
	11th to 20th	Night	22% 7% 2 5% 6% 4 5% 4 4 6% 36%	1415
	21st to end	Night	21% 7% 4 5% 5% 3 5% 4 4 6% 37%	1439
June	1st to 10th	Night	20% 8% 3 6% 6% 5% 7% 6% 5% 8% 27%	1260
	11th to 20th	Night	16% 7% 4 5% 5% 3 5% 5% 6% 8% 38%	1260
	21st to end	Night	20% 8% 3 8% 6% 3 6% 3 4 7% 32%	1260
July	1st to 10th	Night	15% 7% 3 6% 6% 2 6% 5% 6% 8% 36%	1309
	11th to 20th	Night	15% 5% 3 6% 6% 4 5% 5% 7% 8% 35%	1440
	21st to end	Night	13% 7% 3 7% 6% 5% 5% 5% 6% 8% 34%	1574
August	1st to 10th	Night	14% 5% 3 6% 5% 3 4 4 5% 9% 41%	1453
	11th to 20th	Night	16% 6% 3 7% 6% 4 6% 5% 8% 9% 32%	1596
	21st to end	Night	14% 5% 3 6% 6% 3 5% 5% 6% 8% 39%	1842
September	1st to 10th	Night	17% 7% 2 6% 4 3 5% 4 5% 8% 39%	1804
	11th to 20th	Night	18% 7% 3 4 5% 2 4 4 4 6% 42%	1980
	21st to end	Night	19% 7% 3 5% 4 2 4 5% 5% 6% 40%	1980
October	1st to 10th	Night	18% 8% 3 6% 4 3 4 5% 4 7% 38%	1981
	11th to 20th	Night	25% 9% 3 7% 5% 3 3 4 4 6% 29%	2304
	21st to end	Night	23% 10% 3 7% 6% 3 4 4 5% 7% 28%	2574
November	1st to 10th	Night	17% 11% 4 8% 6% 3 5% 4 5% 6% 29%	2407
	11th to 20th	Night	18% 10% 4 8% 6% 3 5% 5% 5% 6% 29%	2508
	21st to end	Night	19% 15% 5% 9% 5% 3 4 5% 4 5% 25%	2812
December	1st to 10th	Night	20% 14% 7% 10% 8% 4 6% 5% 5% 5% 18%	2850
	11th to 20th	Night	19% 14% 5% 9% 8% 3 5% 4 5% 5% 23%	3531
	21st to end	Night	21% 17% 4 8% 6% 3 4 3 3 4 26%	5236

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	60% 10% 12% 14% 4	2487
	11th to 20th	Day	54% 11% 9% 19% 5% 1	2520
	21st to end	Day	50% 8% 12% 22% 8%	2772
February	1st to 10th	Day	57% 6% 10% 16% 9% 1	1540
	11th to 20th	Day	60% 5% 10% 15% 9% 1	1708
	21st to end	Day	55% 6% 7% 20% 10% 2	1480
March	1st to 10th	Day	54% 6% 10% 17% 12% 1	1800
	11th to 20th	Day	55% 6% 9% 17% 11% 1	1912
	21st to end	Day	53% 5% 11% 18% 10% 3	2272
April	1st to 10th	Day	58% 4 11% 14% 10% 3	2160
	11th to 20th	Day	47% 6% 9% 23% 13% 2	2250
	21st to end	Day	53% 5% 11% 16% 12% 3	2340
May	1st to 10th	Day	50% 6% 11% 17% 14% 2	2358
	11th to 20th	Day	49% 6% 10% 22% 11% 1	2482
	21st to end	Day	50% 8% 11% 20% 10% 1	2832
June	1st to 10th	Day	49% 9% 13% 20% 9% 1	2700
	11th to 20th	Day	47% 8% 12% 22% 10% 1	2700
	21st to end	Day	54% 8% 11% 19% 9%	2700
July	1st to 10th	Day	44% 11% 16% 23% 7%	2574
	11th to 20th	Day	43% 9% 14% 26% 8% 1	2445
	21st to end	Day	46% 10% 15% 22% 7%	2591
August	1st to 10th	Day	47% 11% 18% 21% 3	2453
	11th to 20th	Day	42% 9% 18% 23% 9%	2304
	21st to end	Day	41% 9% 15% 26% 9%	2512
September	1st to 10th	Day	42% 7% 14% 25% 11% 1	2156
	11th to 20th	Day	40% 5% 15% 28% 12% 1	1980
	21st to end	Day	44% 5% 13% 26% 11%	1980
October	1st to 10th	Day	48% 6% 11% 27% 9%	1978
	11th to 20th	Day	59% 6% 16% 15% 3	1652
	21st to end	Day	63% 5% 11% 16% 5% 1	1782
November	1st to 10th	Day	55% 7% 13% 18% 8%	1671
	11th to 20th	Day	60% 6% 10% 18% 6%	1672
	21st to end	Day	63% 7% 13% 14% 3	1364
December	1st to 10th	Day	67% 6% 10% 13% 5%	1330
	11th to 20th	Day	61% 6% 9% 18% 7%	1668
	21st to end	Day	61% 7% 12% 11% 6% 2	2431
January	1st to 10th	Night	65% 8% 10% 11% 5%	4457
	11th to 20th	Night	61% 8% 10% 16% 5%	4440
	21st to end	Night	54% 10% 10% 15% 10% 1	4884
February	1st to 10th	Night	57% 6% 10% 16% 10% 1	2623
	11th to 20th	Night	61% 5% 10% 13% 10% 1	2147
	21st to end	Night	58% 5% 7% 17% 13% 1	1776
March	1st to 10th	Night	56% 6% 9% 17% 11% 1	2160
	11th to 20th	Night	56% 7% 9% 15% 11% 2	2047
	21st to end	Night	56% 4 9% 18% 10% 3	2080
April	1st to 10th	Night	60% 4 7% 14% 12% 3	1800
	11th to 20th	Night	49% 5% 9% 22% 13% 2	1657
	21st to end	Night	56% 5% 8% 17% 13% 2	1620
May	1st to 10th	Night	54% 5% 10% 16% 13% 2	1616
	11th to 20th	Night	51% 4 10% 19% 14% 1	1416
	21st to end	Night	50% 6% 10% 18% 15% 1	1440
June	1st to 10th	Night	55% 8% 11% 18% 7% 1	1260
	11th to 20th	Night	45% 8% 10% 23% 11% 3	1260
	21st to end	Night	53% 8% 12% 17% 10%	1260
July	1st to 10th	Night	46% 9% 16% 21% 8%	1272
	11th to 20th	Night	45% 9% 16% 23% 6% 1	1392
	21st to end	Night	47% 10% 16% 20% 8%	1486
August	1st to 10th	Night	40% 9% 19% 28% 3	1443
	11th to 20th	Night	47% 10% 17% 18% 7%	1596
	21st to end	Night	43% 8% 12% 27% 9%	1842
September	1st to 10th	Night	45% 7% 13% 22% 11% 1	1804
	11th to 20th	Night	44% 6% 17% 23% 9%	1980
	21st to end	Night	46% 6% 11% 26% 11%	1980
October	1st to 10th	Night	48% 6% 11% 25% 10% 1	1981
	11th to 20th	Night	57% 6% 13% 18% 5%	2304
	21st to end	Night	58% 6% 13% 16% 7%	2574
November	1st to 10th	Night	56% 7% 12% 18% 6%	2407
	11th to 20th	Night	57% 6% 12% 17% 8%	2508
	21st to end	Night	62% 6% 11% 14% 5% 1	2812
December	1st to 10th	Night	68% 6% 11% 11% 4	2850
	11th to 20th	Night	63% 5% 9% 13% 9%	3532
	21st to end	Night	64% 4 10% 14% 7% 1	5236

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	26% 27% 28% 14% 5% 1	180
	11th to 20th	Day	33% 22% 29% 12% 3 1	180
	21st to end	Day	16% 27% 34% 17% 5% 1	198
February	1st to 10th	Day	25% 22% 36% 11% 4 1	206
	11th to 20th	Day	23% 26% 34% 14% 2	394
	21st to end	Day	27% 21% 28% 20% 3	346
March	1st to 10th	Day	26% 20% 27% 21% 4 1	420
	11th to 20th	Day	25% 16% 32% 20% 6% 1	420
	21st to end	Day	24% 17% 28% 20% 8% 3	462
April	1st to 10th	Day	32% 16% 28% 15% 7% 1	420
	11th to 20th	Day	29% 17% 26% 20% 6% 1	412
	21st to end	Day	26% 17% 32% 17% 5% 3	420
May	1st to 10th	Day	28% 12% 35% 18% 6% 2	423
	11th to 20th	Day	23% 12% 28% 26% 9% 1	447
	21st to end	Day	22% 17% 35% 19% 7% 1	592
June	1st to 10th	Day	23% 14% 31% 24% 8%	630
	11th to 20th	Day	21% 12% 29% 24% 13% 1	630
	21st to end	Day	22% 8% 31% 26% 12% 1	630
July	1st to 10th	Day	17% 12% 31% 28% 11% 2	569
	11th to 20th	Day	17% 11% 33% 27% 10% 2	444
	21st to end	Day	18% 8% 34% 28% 11% 1	488
August	1st to 10th	Day	16% 11% 33% 24% 14% 3	446
	11th to 20th	Day	16% 8% 28% 30% 15% 2	439
	21st to end	Day	20% 14% 24% 23% 14% 6%	495
September	1st to 10th	Day	21% 12% 27% 26% 11% 3	450
	11th to 20th	Day	23% 11% 30% 23% 11% 2	450
	21st to end	Day	22% 13% 27% 24% 10% 5%	450
October	1st to 10th	Day	23% 15% 31% 20% 10% 2	448
	11th to 20th	Day	30% 15% 27% 19% 9% 1	360
	21st to end	Day	35% 17% 30% 13% 5% 1	396
November	1st to 10th	Day	30% 17% 33% 17% 3 1	365
	11th to 20th	Day	27% 20% 27% 19% 7% 1	370
	21st to end	Day	29% 20% 32% 17% 1	214
December	1st to 10th	Day	31% 15% 29% 21% 4 1	180
	11th to 20th	Day	34% 22% 27% 11% 4 2	180
	21st to end	Day	40% 18% 27% 14% 1	198
January	1st to 10th	Night	27% 17% 33% 18% 4	767
	11th to 20th	Night	25% 19% 33% 19% 4	760
	21st to end	Night	18% 17% 35% 24% 5%	836
February	1st to 10th	Night	18% 17% 37% 22% 6%	759
	11th to 20th	Night	25% 18% 37% 14% 5% 1	703
	21st to end	Night	24% 15% 32% 25% 5%	592
March	1st to 10th	Night	23% 12% 37% 23% 5%	720
	11th to 20th	Night	23% 13% 35% 22% 6% 2	720
	21st to end	Night	23% 11% 32% 25% 7% 1	792
April	1st to 10th	Night	31% 13% 26% 23% 6%	720
	11th to 20th	Night	26% 11% 32% 24% 7% 1	593
	21st to end	Night	30% 10% 26% 25% 8%	540
May	1st to 10th	Night	29% 9% 28% 26% 9%	536
	11th to 20th	Night	27% 6% 29% 31% 8% 1	354
	21st to end	Night	27% 6% 34% 25% 7%	389
June	1st to 10th	Night	25% 5% 29% 34% 6%	360
	11th to 20th	Night	17% 4 27% 36% 15%	360
	21st to end	Night	24% 6% 29% 31% 9% 1	360
July	1st to 10th	Night	20% 5% 32% 31% 11%	350
	11th to 20th	Night	18% 4 28% 35% 14% 1	348
	21st to end	Night	14% 6% 31% 38% 11% 1	394
August	1st to 10th	Night	16% 4 25% 40% 15% 1	379
	11th to 20th	Night	18% 6% 24% 37% 14% 1	532
	21st to end	Night	17% 6% 31% 31% 13% 2	654
September	1st to 10th	Night	22% 6% 28% 32% 11% 1	720
	11th to 20th	Night	22% 9% 30% 28% 10% 1	720
	21st to end	Night	22% 10% 28% 29% 11% 1	720
October	1st to 10th	Night	24% 12% 31% 25% 7% 1	720
	11th to 20th	Night	32% 10% 27% 22% 8%	720
	21st to end	Night	28% 15% 32% 19% 6%	792
November	1st to 10th	Night	28% 16% 28% 23% 5% 1	740
	11th to 20th	Night	28% 16% 28% 21% 6% 1	778
	21st to end	Night	28% 15% 33% 19% 4 1	850
December	1st to 10th	Night	31% 15% 31% 18% 5%	850
	11th to 20th	Night	28% 19% 32% 16% 5% 1	850
	21st to end	Night	33% 19% 27% 18% 3 1	935

Page generated at 2024-02-07 06:11:58. Version ac07

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