Mingan
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mingan clear sky chart from 2005-11-06 to 2024-07-08.

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	19% 10% 3 7% 5% 4 4 3 5% 6% 32%	89448
	Night	19% 12% 4 8% 5% 4 4 3 5% 6% 31%	89955
Transparency	Day	55% 3 12% 20% 9% 1	89148
	Night	55% 2 10% 20% 11% 1	89810
Seeing	Day	27% 7% 26% 25% 12% 3	16178
	Night	26% 7% 25% 29% 11% 1	23577

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	10% 16% 5% 9% 3 3 3 3 3 5% 40%	2207
	11th to 20th	Day	12% 16% 5% 13% 7% 6% 4 3 5% 7% 23%	2210
	21st to end	Day	8% 9% 3 9% 6% 5% 5% 4 7% 7% 37%	2600
February	1st to 10th	Day	9% 13% 5% 10% 5% 6% 5% 4 5% 5% 34%	1710
	11th to 20th	Day	10% 16% 5% 10% 6% 6% 4 3 5% 6% 31%	1663
	21st to end	Day	9% 13% 5% 8% 6% 5% 5% 3 4 6% 35%	1413
March	1st to 10th	Day	10% 12% 4 10% 7% 4 6% 4 5% 6% 33%	3246
	11th to 20th	Day	21% 20% 5% 9% 5% 4 4 3 4 4 21%	3480
	21st to end	Day	22% 15% 4 8% 4 4 3 3 4 4 29%	3865
April	1st to 10th	Day	21% 14% 4 8% 5% 4 4 3 4 6% 27%	2280
	11th to 20th	Day	16% 10% 3 7% 5% 4 3 3 5% 6% 38%	2437
	21st to end	Day	24% 9% 3 5% 4 4 3 3 4 5% 36%	2508
May	1st to 10th	Day	28% 9% 3 9% 5% 4 4 3 5% 6% 24%	4425
	11th to 20th	Day	15% 8% 3 8% 5% 5% 4 4 6% 6% 37%	4398
	21st to end	Day	29% 10% 4 7% 4 3 4 3 4 5% 26%	5183
June	1st to 10th	Day	25% 8% 3 7% 4 4 4 3 5% 6% 31%	2850
	11th to 20th	Day	21% 6% 3 6% 4 4 4 4 6% 8% 33%	2850
	21st to end	Day	25% 7% 2 6% 5% 4 4 4 5% 7% 30%	2850
July	1st to 10th	Day	17% 8% 2 7% 6% 5% 5% 4 7% 7% 31%	2809
	11th to 20th	Day	18% 6% 2 5% 4 4 5% 5% 7% 8% 37%	2700
	21st to end	Day	22% 7% 3 7% 5% 5% 4 3 6% 7% 31%	2892
August	1st to 10th	Day	14% 7% 3 7% 5% 5% 5% 5% 7% 8% 34%	2478
	11th to 20th	Day	21% 8% 3 6% 5% 3 4 3 5% 7% 34%	2304
	21st to end	Day	20% 6% 2 6% 5% 4 5% 5% 6% 7% 35%	2553
September	1st to 10th	Day	21% 6% 2 6% 4 5% 4 4 6% 5% 37%	2160
	11th to 20th	Day	25% 8% 3 5% 4 3 3 3 4 5% 38%	2116
	21st to end	Day	21% 8% 2 6% 4 3 3 4 5% 6% 38%	1911
October	1st to 10th	Day	19% 6% 3 7% 4 4 5% 3 5% 6% 39%	1800
	11th to 20th	Day	25% 8% 3 5% 4 4 4 3 5% 7% 32%	1800
	21st to end	Day	25% 11% 3 6% 4 4 3 2 4 5% 31%	1767
November	1st to 10th	Day	22% 9% 4 8% 5% 4 4 3 5% 6% 31%	1485
	11th to 20th	Day	22% 14% 4 7% 4 3 4 3 4 6% 29%	1520
	21st to end	Day	22% 15% 3 8% 4 4 4 3 4 5% 27%	1520
December	1st to 10th	Day	16% 17% 4 8% 5% 5% 3 5% 4 5% 27%	1359
	11th to 20th	Day	20% 12% 5% 8% 5% 4 5% 4 5% 5% 25%	1668
	21st to end	Day	12% 14% 4 9% 5% 4 4 3 5% 6% 35%	2431
January	1st to 10th	Night	11% 15% 5% 10% 5% 4 3 2 5% 5% 34%	4748
	11th to 20th	Night	17% 14% 6% 8% 5% 5% 4 4 5% 7% 26%	4760
	21st to end	Night	6% 12% 5% 12% 5% 4 3 3 5% 6% 39%	5062
February	1st to 10th	Night	8% 16% 5% 10% 5% 5% 4 4 5% 6% 33%	2470
	11th to 20th	Night	13% 16% 4 8% 6% 5% 5% 3 5% 5% 31%	2403
	21st to end	Night	10% 14% 4 10% 7% 5% 4 4 4 5% 33%	2041
March	1st to 10th	Night	9% 12% 4 9% 6% 4 4 4 5% 7% 36%	3576
	11th to 20th	Night	20% 21% 5% 10% 5% 4 4 3 4 4 20%	3479
	21st to end	Night	23% 17% 4 8% 4 4 3 3 4 4 26%	3766
April	1st to 10th	Night	22% 13% 3 8% 5% 4 4 4 5% 6% 26%	1900
	11th to 20th	Night	19% 11% 3 7% 4 4 4 3 6% 5% 35%	1691
	21st to end	Night	25% 9% 3 6% 5% 4 4 3 4 4 33%	1672
May	1st to 10th	Night	30% 11% 4 8% 5% 4 4 3 5% 5% 23%	2525
	11th to 20th	Night	16% 7% 3 8% 5% 4 5% 4 5% 7% 37%	2506
	21st to end	Night	26% 11% 3 8% 5% 5% 4 3 5% 5% 25%	2432
June	1st to 10th	Night	27% 7% 2 6% 4 4 3 4 6% 5% 32%	1330
	11th to 20th	Night	23% 8% 2 7% 5% 4 4 4 5% 8% 31%	1330
	21st to end	Night	26% 8% 2 7% 5% 5% 5% 3 6% 6% 27%	1330
July	1st to 10th	Night	17% 8% 3 8% 5% 5% 5% 5% 5% 7% 33%	1316
	11th to 20th	Night	18% 9% 3 5% 4 3 4 4 6% 8% 37%	1260
	21st to end	Night	21% 7% 3 7% 5% 4 5% 4 7% 8% 29%	1407
August	1st to 10th	Night	19% 8% 2 6% 5% 3 5% 4 6% 9% 33%	1458
	11th to 20th	Night	22% 6% 3 7% 4 4 5% 4 4 6% 34%	1596
	21st to end	Night	18% 8% 3 8% 5% 4 4 4 6% 7% 32%	1802
September	1st to 10th	Night	23% 7% 2 5% 4 3 3 4 5% 6% 39%	1800
	11th to 20th	Night	24% 5% 2 7% 4 4 4 3 5% 6% 37%	1843
	21st to end	Night	23% 6% 3 6% 3 3 4 2 5% 6% 38%	2048
October	1st to 10th	Night	23% 9% 2 7% 4 3 3 3 6% 5% 35%	2160
	11th to 20th	Night	30% 8% 3 7% 4 4 4 3 5% 5% 29%	2160
	21st to end	Night	25% 10% 3 7% 4 3 4 3 4 5% 32%	2586
November	1st to 10th	Night	24% 11% 3 7% 4 4 4 3 5% 6% 30%	2593
	11th to 20th	Night	24% 14% 4 8% 5% 4 3 3 4 5% 26%	2660
	21st to end	Night	23% 17% 4 7% 4 4 3 3 4 5% 26%	2660
December	1st to 10th	Night	20% 15% 4 8% 4 4 4 4 4 4 27%	2818
	11th to 20th	Night	22% 14% 5% 8% 4 4 4 4 4 5% 28%	3531
	21st to end	Night	13% 15% 4 8% 4 4 4 3 6% 7% 34%	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	48% 2 7% 21% 19% 3	2208
	11th to 20th	Day	62% 1 10% 20% 6% 1	2210
	21st to end	Day	44% 3 12% 17% 17% 7%	2600
February	1st to 10th	Day	53% 2 9% 20% 14% 2	1710
	11th to 20th	Day	56% 2 10% 19% 13% 1	1671
	21st to end	Day	52% 2 9% 21% 14% 2	1413
March	1st to 10th	Day	53% 2 11% 20% 13% 1	3250
	11th to 20th	Day	72% 2 5% 12% 8% 2	3480
	21st to end	Day	62% 2 7% 20% 8% 3	3865
April	1st to 10th	Day	61% 2 7% 15% 12% 3	2280
	11th to 20th	Day	49% 3 10% 23% 13% 3	2437
	21st to end	Day	54% 2 11% 20% 13% 1	2508
May	1st to 10th	Day	64% 1 9% 20% 5% 1	4440
	11th to 20th	Day	50% 3 12% 26% 9% 1	4402
	21st to end	Day	64% 2 9% 19% 6% 1	5183
June	1st to 10th	Day	57% 3 11% 19% 10% 1	2850
	11th to 20th	Day	50% 4 13% 22% 10% 1	2850
	21st to end	Day	54% 3 12% 21% 9%	2850
July	1st to 10th	Day	49% 4 18% 21% 8%	2734
	11th to 20th	Day	44% 4 17% 27% 8%	2619
	21st to end	Day	52% 5% 15% 22% 6%	2730
August	1st to 10th	Day	46% 6% 26% 18% 5%	2464
	11th to 20th	Day	51% 3 18% 22% 6%	2304
	21st to end	Day	49% 4 19% 23% 5%	2553
September	1st to 10th	Day	47% 4 14% 26% 9%	2160
	11th to 20th	Day	51% 4 15% 22% 9%	2116
	21st to end	Day	49% 4 12% 24% 11%	1911
October	1st to 10th	Day	47% 3 18% 23% 9% 1	1800
	11th to 20th	Day	54% 3 13% 24% 8%	1800
	21st to end	Day	58% 3 10% 18% 10% 1	1767
November	1st to 10th	Day	55% 4 12% 18% 11% 1	1485
	11th to 20th	Day	59% 3 12% 19% 7%	1520
	21st to end	Day	62% 3 9% 17% 9%	1520
December	1st to 10th	Day	59% 3 10% 20% 6% 1	1359
	11th to 20th	Day	62% 2 9% 19% 8% 1	1668
	21st to end	Day	52% 1 11% 20% 13% 4	2431
January	1st to 10th	Night	52% 2 8% 20% 17% 2	4748
	11th to 20th	Night	60% 2 7% 20% 10% 1	4760
	21st to end	Night	47% 1 8% 23% 19% 2	5062
February	1st to 10th	Night	52% 2 8% 19% 14% 4	2470
	11th to 20th	Night	56% 3 9% 17% 13% 1	2406
	21st to end	Night	54% 2 8% 19% 14% 3	2041
March	1st to 10th	Night	50% 1 8% 23% 16% 2	3585
	11th to 20th	Night	69% 2 5% 14% 9% 1	3480
	21st to end	Night	63% 2 6% 15% 8% 5%	3766
April	1st to 10th	Night	60% 2 7% 15% 13% 3	1900
	11th to 20th	Night	52% 2 9% 20% 14% 3	1691
	21st to end	Night	55% 1 10% 15% 17% 1	1672
May	1st to 10th	Night	64% 1 7% 20% 6% 1	2530
	11th to 20th	Night	48% 2 13% 29% 8% 1	2507
	21st to end	Night	64% 2 8% 17% 9% 1	2433
June	1st to 10th	Night	55% 2 11% 21% 9% 1	1330
	11th to 20th	Night	52% 4 14% 20% 10% 1	1330
	21st to end	Night	58% 4 11% 19% 7% 1	1330
July	1st to 10th	Night	50% 5% 17% 21% 7%	1281
	11th to 20th	Night	47% 4 13% 27% 9% 1	1218
	21st to end	Night	52% 5% 16% 21% 6%	1329
August	1st to 10th	Night	49% 5% 22% 19% 5%	1447
	11th to 20th	Night	51% 4 19% 20% 6%	1596
	21st to end	Night	50% 4 16% 24% 5%	1802
September	1st to 10th	Night	47% 3 14% 25% 11% 1	1800
	11th to 20th	Night	50% 3 14% 25% 8%	1843
	21st to end	Night	49% 3 11% 24% 12% 1	2048
October	1st to 10th	Night	52% 3 10% 23% 10% 2	2160
	11th to 20th	Night	58% 2 11% 21% 8%	2160
	21st to end	Night	57% 2 10% 20% 8% 2	2586
November	1st to 10th	Night	56% 3 12% 17% 11% 2	2593
	11th to 20th	Night	61% 2 13% 16% 7%	2660
	21st to end	Night	63% 2 11% 15% 9%	2660
December	1st to 10th	Night	60% 3 10% 18% 9%	2818
	11th to 20th	Night	60% 2 6% 21% 10% 1	3532
	21st to end	Night	51% 2 13% 20% 12% 2	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	22% 8% 33% 23% 12% 3	180
	11th to 20th	Day	28% 9% 28% 22% 11% 2	180
	21st to end	Day	19% 10% 29% 27% 14% 3	259
February	1st to 10th	Day	18% 7% 37% 26% 9% 3	370
	11th to 20th	Day	17% 9% 30% 29% 13% 2	366
	21st to end	Day	19% 7% 32% 27% 11% 4	307
March	1st to 10th	Day	18% 9% 32% 30% 8% 2	424
	11th to 20th	Day	25% 7% 27% 26% 11% 4	460
	21st to end	Day	26% 12% 27% 22% 10% 2	506
April	1st to 10th	Day	30% 11% 28% 24% 6% 1	460
	11th to 20th	Day	25% 7% 30% 25% 10% 4	452
	21st to end	Day	30% 7% 26% 22% 12% 4	498
May	1st to 10th	Day	32% 4 24% 25% 12% 4	653
	11th to 20th	Day	25% 7% 29% 25% 10% 5%	674
	21st to end	Day	31% 9% 28% 22% 8% 1	735
June	1st to 10th	Day	30% 6% 24% 27% 11% 1	680
	11th to 20th	Day	28% 5% 25% 25% 13% 4	680
	21st to end	Day	30% 6% 24% 24% 13% 3	680
July	1st to 10th	Day	23% 5% 24% 30% 15% 4	657
	11th to 20th	Day	24% 4 21% 33% 16% 3	618
	21st to end	Day	30% 4 18% 27% 18% 4	685
August	1st to 10th	Day	22% 3 19% 32% 19% 5%	597
	11th to 20th	Day	24% 6% 19% 31% 17% 4	439
	21st to end	Day	23% 5% 27% 27% 13% 5%	495
September	1st to 10th	Day	26% 8% 24% 27% 12% 3	450
	11th to 20th	Day	31% 9% 23% 23% 11% 2	450
	21st to end	Day	28% 7% 34% 18% 10% 2	415
October	1st to 10th	Day	24% 8% 34% 22% 9% 4	360
	11th to 20th	Day	33% 9% 26% 18% 11% 4	360
	21st to end	Day	34% 10% 21% 21% 11% 4	396
November	1st to 10th	Day	30% 12% 27% 24% 6% 1	365
	11th to 20th	Day	34% 8% 25% 24% 6% 2	370
	21st to end	Day	30% 11% 28% 23% 7% 1	370
December	1st to 10th	Day	23% 11% 23% 26% 12% 5%	209
	11th to 20th	Day	23% 17% 29% 22% 7% 2	180
	21st to end	Day	23% 10% 37% 23% 8%	198
January	1st to 10th	Night	23% 6% 31% 30% 9% 1	850
	11th to 20th	Night	25% 11% 28% 27% 8% 1	850
	21st to end	Night	19% 10% 34% 27% 10% 1	913
February	1st to 10th	Night	16% 11% 34% 28% 10% 1	760
	11th to 20th	Night	21% 8% 31% 30% 9% 1	743
	21st to end	Night	17% 9% 30% 27% 15% 2	628
March	1st to 10th	Night	17% 11% 32% 29% 11% 1	760
	11th to 20th	Night	22% 8% 30% 27% 11% 1	760
	21st to end	Night	23% 12% 27% 27% 9% 2	811
April	1st to 10th	Night	28% 7% 27% 27% 10%	570
	11th to 20th	Night	24% 6% 29% 28% 12% 1	564
	21st to end	Night	29% 5% 25% 29% 10% 2	570
May	1st to 10th	Night	29% 2 20% 33% 14% 2	570
	11th to 20th	Night	22% 4 24% 31% 17% 2	562
	21st to end	Night	27% 5% 23% 32% 13% 1	429
June	1st to 10th	Night	30% 4 18% 37% 10% 1	380
	11th to 20th	Night	28% 3 16% 32% 20% 1	380
	21st to end	Night	31% 2 16% 34% 17% 1	380
July	1st to 10th	Night	23% 4 16% 37% 17% 2	366
	11th to 20th	Night	23% 2 13% 45% 16% 1	348
	21st to end	Night	27% 1 12% 35% 22% 3	424
August	1st to 10th	Night	24% 1 12% 37% 23% 3	538
	11th to 20th	Night	24% 3 15% 35% 23% 1	532
	21st to end	Night	22% 3 18% 36% 19% 2	594
September	1st to 10th	Night	27% 4 24% 30% 13% 2	540
	11th to 20th	Night	28% 5% 22% 32% 11% 2	583
	21st to end	Night	27% 7% 24% 32% 10%	720
October	1st to 10th	Night	30% 6% 27% 28% 8% 1	720
	11th to 20th	Night	36% 5% 20% 26% 12% 1	720
	21st to end	Night	31% 8% 23% 29% 9% 1	847
November	1st to 10th	Night	33% 10% 30% 21% 6% 1	830
	11th to 20th	Night	34% 9% 23% 26% 7% 2	850
	21st to end	Night	33% 9% 25% 27% 5% 1	850
December	1st to 10th	Night	29% 10% 28% 24% 7% 1	850
	11th to 20th	Night	26% 13% 34% 20% 6% 1	850
	21st to end	Night	26% 12% 29% 25% 7% 1	935

Page generated at 2024-07-05 11:05:41. Version ac07

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