Port-Cartier
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Port-Cartier clear sky chart from 2005-11-06 to 2026-03-18.

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% 10% 3 7% 5% 4 4 4 5% 6% 33%	131206
	Night	17% 12% 4 8% 5% 4 4 3 5% 6% 33%	130524
Transparency	Day	32% 38% 8% 14% 6% 1	134606
	Night	34% 37% 7% 14% 7% 1	135212
Seeing	Day	25% 12% 28% 23% 9% 2	17868
	Night	24% 9% 27% 29% 10% 1	25725

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	14% 19% 5% 11% 5% 4 4 3 5% 5% 26%	4093
	11th to 20th	Day	9% 18% 6% 12% 4 4 3 2 4 6% 31%	4084
	21st to end	Day	4 7% 4 10% 6% 5% 5% 4 5% 6% 44%	5050
February	1st to 10th	Day	6% 11% 4 10% 7% 5% 4 4 5% 7% 36%	1806
	11th to 20th	Day	10% 16% 5% 10% 5% 4 5% 4 5% 6% 30%	1843
	21st to end	Day	8% 14% 4 9% 6% 4 5% 4 5% 7% 33%	1620
March	1st to 10th	Day	13% 14% 4 8% 5% 5% 4 4 5% 6% 30%	4711
	11th to 20th	Day	20% 18% 4 8% 5% 4 4 4 4 5% 24%	5057
	21st to end	Day	20% 17% 4 8% 4 4 3 3 4 5% 29%	5466
April	1st to 10th	Day	19% 13% 3 8% 6% 5% 5% 3 5% 5% 28%	2454
	11th to 20th	Day	15% 11% 4 8% 5% 5% 4 3 6% 7% 34%	2572
	21st to end	Day	24% 10% 3 6% 4 4 4 3 5% 5% 34%	2600
May	1st to 10th	Day	24% 9% 3 7% 4 4 4 3 5% 5% 32%	6116
	11th to 20th	Day	24% 8% 2 6% 4 4 4 3 5% 6% 34%	6673
	21st to end	Day	26% 8% 3 6% 4 5% 4 3 4 6% 30%	7451
June	1st to 10th	Day	25% 8% 3 5% 5% 4 4 4 5% 6% 31%	3000
	11th to 20th	Day	20% 7% 3 6% 5% 5% 4 4 7% 7% 33%	3000
	21st to end	Day	27% 8% 2 6% 5% 4 4 4 5% 7% 29%	3000
July	1st to 10th	Day	16% 6% 3 7% 5% 4 5% 4 6% 7% 35%	6820
	11th to 20th	Day	15% 8% 3 7% 5% 5% 6% 5% 7% 8% 31%	6820
	21st to end	Day	13% 5% 2 5% 5% 5% 5% 4 6% 8% 43%	7411
August	1st to 10th	Day	15% 5% 2 6% 6% 6% 6% 5% 7% 8% 34%	4367
	11th to 20th	Day	22% 7% 3 7% 5% 5% 5% 5% 7% 7% 29%	4175
	21st to end	Day	14% 5% 2 6% 4 5% 4 4 6% 8% 41%	4675
September	1st to 10th	Day	20% 5% 2 7% 4 4 5% 3 6% 7% 36%	2475
	11th to 20th	Day	25% 5% 2 4 4 3 3 4 4 6% 40%	2200
	21st to end	Day	21% 6% 2 5% 4 4 3 3 5% 7% 39%	2200
October	1st to 10th	Day	19% 7% 2 7% 3 5% 4 4 5% 6% 37%	2029
	11th to 20th	Day	26% 8% 3 7% 5% 4 5% 3 5% 6% 29%	1973
	21st to end	Day	27% 8% 3 7% 6% 4 4 3 4 5% 28%	1980
November	1st to 10th	Day	20% 10% 3 6% 4 5% 4 4 7% 5% 31%	1655
	11th to 20th	Day	21% 14% 4 7% 4 4 5% 3 4 5% 28%	1680
	21st to end	Day	20% 16% 4 8% 5% 5% 3 3 4 4 29%	1559
December	1st to 10th	Day	14% 14% 3 11% 6% 5% 5% 4 5% 4 29%	2350
	11th to 20th	Day	17% 11% 3 9% 4 4 4 3 4 5% 34%	2688
	21st to end	Day	15% 12% 4 8% 4 3 3 3 4 6% 38%	3553
January	1st to 10th	Night	15% 21% 5% 8% 5% 4 4 3 4 4 26%	8831
	11th to 20th	Night	11% 16% 6% 10% 5% 4 5% 4 6% 6% 28%	8831
	21st to end	Night	4 9% 4 9% 5% 4 4 4 5% 7% 45%	9119
February	1st to 10th	Night	7% 12% 5% 10% 6% 5% 5% 3 5% 6% 36%	2812
	11th to 20th	Night	12% 18% 5% 9% 5% 4 4 3 5% 6% 30%	2663
	21st to end	Night	11% 13% 6% 8% 5% 5% 5% 4 4 5% 34%	2181
March	1st to 10th	Night	15% 14% 4 8% 5% 4 4 3 4 5% 33%	5349
	11th to 20th	Night	20% 18% 4 9% 5% 4 4 4 4 5% 23%	5057
	21st to end	Night	20% 16% 5% 10% 5% 4 4 3 4 4 26%	5466
April	1st to 10th	Night	22% 11% 3 8% 4 5% 5% 3 4 4 30%	1941
	11th to 20th	Night	21% 9% 3 6% 4 3 4 3 4 5% 37%	1778
	21st to end	Night	24% 10% 3 6% 3 4 3 2 3 5% 36%	1800
May	1st to 10th	Night	28% 10% 3 6% 4 4 3 3 4 5% 30%	3834
	11th to 20th	Night	25% 8% 3 7% 4 4 4 4 5% 4 31%	3284
	21st to end	Night	25% 10% 3 6% 4 3 4 3 6% 7% 28%	3446
June	1st to 10th	Night	24% 8% 2 6% 5% 4 4 4 6% 6% 32%	1400
	11th to 20th	Night	21% 7% 2 6% 4 4 6% 5% 6% 6% 34%	1400
	21st to end	Night	27% 7% 4 7% 4 3 3 3 6% 7% 29%	1400
July	1st to 10th	Night	15% 8% 2 6% 5% 4 5% 4 7% 9% 37%	3160
	11th to 20th	Night	17% 7% 3 6% 5% 5% 4 4 6% 8% 35%	3160
	21st to end	Night	11% 5% 2 6% 5% 4 5% 4 6% 7% 46%	3459
August	1st to 10th	Night	17% 7% 3 7% 4 4 4 5% 6% 7% 35%	2749
	11th to 20th	Night	17% 8% 3 9% 6% 5% 5% 5% 6% 7% 29%	2872
	21st to end	Night	15% 6% 3 6% 4 5% 5% 4 6% 6% 40%	3223
September	1st to 10th	Night	21% 6% 2 5% 4 4 5% 3 6% 5% 39%	1923
	11th to 20th	Night	22% 6% 3 4 4 3 4 3 4 6% 42%	2200
	21st to end	Night	21% 6% 2 5% 4 3 3 3 5% 6% 43%	2200
October	1st to 10th	Night	22% 8% 3 6% 4 4 3 3 5% 6% 37%	2370
	11th to 20th	Night	27% 9% 3 7% 4 3 3 4 4 5% 31%	2425
	21st to end	Night	25% 9% 3 7% 4 4 4 3 4 5% 31%	2860
November	1st to 10th	Night	24% 10% 3 6% 5% 4 4 3 5% 5% 31%	2863
	11th to 20th	Night	22% 12% 3 7% 5% 4 4 4 4 5% 29%	2940
	21st to end	Night	21% 15% 5% 9% 5% 4 4 3 5% 5% 25%	3060
December	1st to 10th	Night	13% 15% 5% 9% 5% 4 4 3 5% 6% 32%	5060
	11th to 20th	Night	21% 11% 3 7% 4 4 4 3 4 5% 34%	5741
	21st to end	Night	14% 12% 5% 10% 5% 5% 4 4 4 5% 32%	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	48% 21% 5% 18% 6% 1	4094
	11th to 20th	Day	45% 23% 11% 17% 4	4110
	21st to end	Day	30% 25% 10% 15% 18% 2	5050
February	1st to 10th	Day	18% 58% 5% 11% 6% 2	1806
	11th to 20th	Day	21% 59% 4 10% 6%	1851
	21st to end	Day	22% 59% 2 12% 4 1	1620
March	1st to 10th	Day	40% 30% 5% 12% 11% 1	4715
	11th to 20th	Day	49% 31% 5% 9% 5% 2	5057
	21st to end	Day	43% 30% 4 12% 9% 2	5466
April	1st to 10th	Day	19% 62% 3 7% 8% 1	2454
	11th to 20th	Day	20% 62% 3 8% 5% 1	2572
	21st to end	Day	25% 62% 5% 5% 3 1	2600
May	1st to 10th	Day	38% 31% 7% 18% 5% 1	6127
	11th to 20th	Day	39% 31% 10% 15% 6% 1	6677
	21st to end	Day	40% 31% 8% 13% 6% 1	7451
June	1st to 10th	Day	21% 62% 4 9% 3	3000
	11th to 20th	Day	19% 63% 5% 8% 5%	3000
	21st to end	Day	19% 61% 5% 9% 4 1	3000
July	1st to 10th	Day	33% 28% 10% 22% 7%	6745
	11th to 20th	Day	37% 30% 13% 14% 6%	6739
	21st to end	Day	25% 29% 13% 25% 8% 1	7199
August	1st to 10th	Day	26% 40% 13% 16% 4	4353
	11th to 20th	Day	36% 39% 12% 9% 3	4214
	21st to end	Day	22% 38% 13% 18% 8%	4675
September	1st to 10th	Day	19% 58% 9% 11% 3	2475
	11th to 20th	Day	22% 58% 6% 11% 3	2200
	21st to end	Day	15% 57% 7% 13% 7%	2200
October	1st to 10th	Day	34% 37% 8% 16% 4 1	3302
	11th to 20th	Day	30% 38% 9% 18% 5%	3189
	21st to end	Day	29% 38% 12% 13% 9%	3180
November	1st to 10th	Day	26% 54% 7% 7% 6%	1655
	11th to 20th	Day	29% 54% 5% 8% 4	1680
	21st to end	Day	28% 55% 5% 8% 4	1559
December	1st to 10th	Day	37% 36% 8% 9% 10%	2350
	11th to 20th	Day	38% 32% 7% 17% 6%	2688
	21st to end	Day	34% 27% 8% 20% 9% 3	3553
January	1st to 10th	Night	51% 22% 7% 14% 6% 1	8831
	11th to 20th	Night	45% 24% 9% 16% 5% 1	8880
	21st to end	Night	28% 24% 12% 21% 15%	9119
February	1st to 10th	Night	17% 59% 4 10% 8% 2	2812
	11th to 20th	Night	23% 58% 3 9% 6%	2666
	21st to end	Night	21% 59% 2 9% 8% 1	2181
March	1st to 10th	Night	38% 29% 6% 9% 16% 1	5358
	11th to 20th	Night	51% 30% 4 8% 7% 1	5058
	21st to end	Night	47% 30% 3 8% 10% 2	5466
April	1st to 10th	Night	19% 62% 1 8% 8% 2	1941
	11th to 20th	Night	21% 62% 2 7% 7% 2	1778
	21st to end	Night	25% 61% 3 6% 5%	1800
May	1st to 10th	Night	41% 30% 6% 12% 8% 3	3840
	11th to 20th	Night	41% 31% 6% 13% 8%	3285
	21st to end	Night	40% 31% 7% 15% 7%	3447
June	1st to 10th	Night	18% 62% 4 10% 6%	1400
	11th to 20th	Night	20% 62% 3 9% 5%	1400
	21st to end	Night	18% 62% 5% 9% 5% 1	1400
July	1st to 10th	Night	30% 29% 11% 19% 9% 2	3125
	11th to 20th	Night	34% 29% 14% 17% 6%	3118
	21st to end	Night	23% 29% 15% 22% 10% 1	3356
August	1st to 10th	Night	28% 39% 13% 17% 3	2739
	11th to 20th	Night	34% 40% 13% 11% 2	2899
	21st to end	Night	24% 40% 8% 19% 8%	3223
September	1st to 10th	Night	18% 57% 6% 13% 5% 1	1923
	11th to 20th	Night	22% 57% 8% 10% 4	2200
	21st to end	Night	16% 57% 5% 14% 7%	2200
October	1st to 10th	Night	34% 37% 6% 18% 4	3877
	11th to 20th	Night	33% 38% 10% 13% 5%	3948
	21st to end	Night	35% 39% 6% 16% 4	4610
November	1st to 10th	Night	27% 53% 6% 8% 5%	2863
	11th to 20th	Night	26% 55% 6% 9% 3	2940
	21st to end	Night	31% 54% 5% 6% 4	3060
December	1st to 10th	Night	34% 36% 9% 13% 7%	5060
	11th to 20th	Night	38% 32% 7% 16% 6%	5742
	21st to end	Night	39% 28% 9% 16% 6% 3	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	23% 11% 29% 21% 15% 1	220
	11th to 20th	Day	21% 13% 25% 23% 15% 3	220
	21st to end	Day	15% 15% 27% 28% 12% 3	242
February	1st to 10th	Day	12% 12% 34% 28% 9% 4	346
	11th to 20th	Day	15% 13% 38% 26% 7% 1	426
	21st to end	Day	18% 11% 36% 26% 9% 2	388
March	1st to 10th	Day	21% 16% 30% 25% 7% 2	540
	11th to 20th	Day	27% 12% 28% 23% 8% 2	528
	21st to end	Day	27% 17% 28% 21% 6% 1	550
April	1st to 10th	Day	26% 18% 29% 20% 6% 1	500
	11th to 20th	Day	23% 11% 34% 22% 8% 2	492
	21st to end	Day	32% 13% 29% 17% 7% 2	500
May	1st to 10th	Day	28% 9% 28% 24% 9% 2	603
	11th to 20th	Day	27% 10% 29% 21% 12% 2	724
	21st to end	Day	30% 14% 27% 22% 7% 1	790
June	1st to 10th	Day	30% 9% 30% 22% 8% 1	730
	11th to 20th	Day	25% 13% 27% 22% 11% 2	730
	21st to end	Day	29% 11% 27% 23% 8% 2	730
July	1st to 10th	Day	24% 11% 27% 25% 11% 3	720
	11th to 20th	Day	21% 9% 28% 30% 11% 2	718
	21st to end	Day	23% 8% 26% 28% 13% 2	790
August	1st to 10th	Day	23% 7% 27% 30% 10% 4	526
	11th to 20th	Day	23% 8% 29% 27% 12% 3	519
	21st to end	Day	21% 9% 28% 26% 13% 3	583
September	1st to 10th	Day	25% 14% 28% 22% 9% 3	530
	11th to 20th	Day	28% 9% 31% 21% 8% 3	530
	21st to end	Day	24% 14% 27% 22% 9% 3	530
October	1st to 10th	Day	23% 16% 29% 21% 10% 2	435
	11th to 20th	Day	32% 12% 25% 17% 10% 4	420
	21st to end	Day	34% 11% 24% 19% 11% 2	462
November	1st to 10th	Day	30% 17% 28% 20% 5%	425
	11th to 20th	Day	30% 10% 29% 20% 9% 1	430
	21st to end	Day	28% 18% 28% 19% 7%	309
December	1st to 10th	Day	20% 10% 24% 30% 12% 3	220
	11th to 20th	Day	20% 20% 30% 22% 7% 1	220
	21st to end	Day	23% 19% 25% 24% 9% 1	242
January	1st to 10th	Night	22% 8% 32% 29% 9%	950
	11th to 20th	Night	21% 11% 30% 30% 8%	950
	21st to end	Night	14% 10% 34% 34% 7% 1	935
February	1st to 10th	Night	13% 12% 36% 29% 10% 1	840
	11th to 20th	Night	21% 12% 31% 26% 9% 1	823
	21st to end	Night	17% 11% 33% 27% 9% 3	692
March	1st to 10th	Night	20% 12% 29% 30% 8% 1	840
	11th to 20th	Night	21% 13% 28% 29% 9%	829
	21st to end	Night	23% 11% 31% 25% 8% 1	880
April	1st to 10th	Night	28% 11% 29% 26% 7%	680
	11th to 20th	Night	24% 10% 28% 28% 9% 1	594
	21st to end	Night	30% 8% 25% 27% 9% 1	600
May	1st to 10th	Night	30% 7% 25% 31% 7% 1	600
	11th to 20th	Night	25% 7% 23% 33% 11% 1	462
	21st to end	Night	26% 9% 26% 31% 8%	433
June	1st to 10th	Night	27% 6% 23% 36% 9%	400
	11th to 20th	Night	26% 2 22% 34% 16% 1	400
	21st to end	Night	28% 6% 22% 35% 9% 2	400
July	1st to 10th	Night	25% 4 24% 33% 14% 1	390
	11th to 20th	Night	23% 5% 16% 41% 15% 1	388
	21st to end	Night	20% 5% 17% 40% 17% 1	438
August	1st to 10th	Night	23% 2 17% 36% 20% 1	496
	11th to 20th	Night	21% 4 19% 40% 16% 1	592
	21st to end	Night	20% 6% 18% 37% 16% 2	660
September	1st to 10th	Night	24% 5% 25% 33% 12% 1	603
	11th to 20th	Night	25% 6% 24% 32% 12% 2	800
	21st to end	Night	25% 8% 25% 31% 11% 1	800
October	1st to 10th	Night	27% 9% 28% 26% 9% 1	800
	11th to 20th	Night	30% 7% 25% 23% 15% 1	800
	21st to end	Night	31% 7% 25% 27% 9% 1	880
November	1st to 10th	Night	30% 10% 30% 25% 5%	925
	11th to 20th	Night	28% 11% 28% 25% 9% 1	950
	21st to end	Night	29% 9% 29% 25% 8%	950
December	1st to 10th	Night	25% 11% 27% 28% 9% 1	950
	11th to 20th	Night	24% 13% 33% 23% 6%	950
	21st to end	Night	23% 10% 33% 25% 7% 1	1045

Page generated at 2026-03-15 02:23:52. Version ac07

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