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 2024-12-06.

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%	102109
	Night	18% 11% 4 8% 5% 4 4 4 5% 6% 33%	97706
Transparency	Day	27% 47% 7% 12% 5% 1	105534
	Night	29% 47% 6% 12% 6% 1	102371
Seeing	Day	25% 11% 28% 23% 10% 2	16275
	Night	24% 9% 27% 29% 10% 1	23973

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% 14% 4 10% 5% 4 5% 3 5% 4 34%	2207
	11th to 20th	Day	11% 12% 5% 12% 5% 4 4 3 4 5% 34%	2210
	21st to end	Day	6% 9% 4 10% 6% 5% 5% 3 5% 5% 43%	2724
February	1st to 10th	Day	7% 11% 4 11% 8% 5% 4 4 5% 6% 36%	1634
	11th to 20th	Day	10% 16% 5% 10% 5% 4 5% 4 5% 7% 29%	1663
	21st to end	Day	9% 14% 4 9% 6% 4 6% 4 5% 7% 33%	1470
March	1st to 10th	Day	11% 15% 4 8% 5% 5% 5% 4 6% 6% 32%	3206
	11th to 20th	Day	20% 19% 5% 8% 6% 5% 4 3 4 3 22%	3480
	21st to end	Day	22% 15% 4 8% 4 4 3 3 4 5% 28%	3816
April	1st to 10th	Day	20% 13% 3 8% 6% 5% 4 3 5% 5% 28%	2331
	11th to 20th	Day	15% 11% 3 8% 5% 5% 4 3 6% 7% 34%	2442
	21st to end	Day	23% 10% 3 6% 4 4 4 3 5% 5% 34%	2470
May	1st to 10th	Day	23% 9% 3 7% 5% 5% 5% 4 5% 6% 30%	4266
	11th to 20th	Day	21% 9% 2 7% 4 4 4 3 5% 6% 34%	4641
	21st to end	Day	27% 10% 3 6% 5% 5% 5% 4 5% 6% 25%	5185
June	1st to 10th	Day	25% 9% 3 5% 5% 4 4 4 5% 6% 30%	2850
	11th to 20th	Day	20% 7% 3 6% 4 5% 4 5% 7% 7% 33%	2850
	21st to end	Day	27% 8% 2 5% 5% 4 4 4 5% 7% 28%	2850
July	1st to 10th	Day	16% 6% 2 6% 5% 4 5% 4 6% 7% 39%	4760
	11th to 20th	Day	13% 8% 3 6% 5% 5% 6% 5% 8% 8% 33%	4760
	21st to end	Day	14% 5% 2 5% 4 5% 5% 5% 7% 8% 41%	5145
August	1st to 10th	Day	16% 5% 2 7% 6% 6% 6% 5% 7% 8% 33%	4233
	11th to 20th	Day	22% 7% 3 7% 5% 5% 5% 5% 7% 7% 27%	4045
	21st to end	Day	14% 5% 2 6% 4 5% 4 4 6% 8% 42%	4532
September	1st to 10th	Day	20% 5% 2 7% 4 4 5% 3 6% 7% 35%	2351
	11th to 20th	Day	26% 5% 2 4 4 3 3 3 4 6% 39%	2090
	21st to end	Day	22% 6% 2 5% 4 4 3 3 5% 7% 38%	2090
October	1st to 10th	Day	20% 7% 2 7% 3 4 4 4 5% 6% 37%	1928
	11th to 20th	Day	26% 8% 3 7% 5% 4 4 3 5% 6% 29%	1875
	21st to end	Day	27% 8% 3 7% 6% 4 4 3 4 5% 29%	1881
November	1st to 10th	Day	20% 10% 3 6% 4 5% 4 4 7% 5% 31%	1575
	11th to 20th	Day	22% 14% 4 7% 4 5% 5% 3 4 5% 29%	1600
	21st to end	Day	20% 16% 4 8% 5% 5% 3 2 4 4 29%	1485
December	1st to 10th	Day	18% 13% 3 7% 5% 5% 4 4 6% 5% 30%	1365
	11th to 20th	Day	17% 13% 4 9% 4 3 3 2 3 5% 38%	1668
	21st to end	Day	14% 13% 4 8% 4 3 3 3 4 6% 36%	2431
January	1st to 10th	Night	11% 16% 4 10% 7% 5% 5% 3 4 4 31%	4748
	11th to 20th	Night	14% 13% 5% 9% 5% 5% 5% 4 5% 6% 29%	4760
	21st to end	Night	6% 10% 4 9% 5% 4 4 3 5% 6% 45%	4918
February	1st to 10th	Night	8% 13% 5% 10% 7% 4 5% 3 5% 5% 36%	2545
	11th to 20th	Night	12% 17% 5% 9% 5% 4 4 3 5% 6% 30%	2403
	21st to end	Night	12% 13% 6% 8% 5% 5% 5% 4 5% 5% 32%	1979
March	1st to 10th	Night	11% 13% 4 10% 7% 5% 5% 3 5% 6% 33%	3634
	11th to 20th	Night	19% 20% 5% 9% 5% 4 3 3 4 4 22%	3479
	21st to end	Night	23% 17% 4 8% 4 3 4 3 4 4 26%	3816
April	1st to 10th	Night	23% 11% 3 8% 5% 5% 5% 3 4 4 30%	1844
	11th to 20th	Night	21% 9% 3 6% 4 3 4 3 4 5% 37%	1688
	21st to end	Night	25% 10% 3 6% 3 4 3 2 3 5% 37%	1710
May	1st to 10th	Night	28% 11% 3 7% 5% 4 4 4 4 6% 23%	2679
	11th to 20th	Night	20% 8% 3 8% 5% 5% 5% 4 6% 5% 32%	2292
	21st to end	Night	25% 12% 4 8% 5% 4 4 3 5% 5% 25%	2401
June	1st to 10th	Night	24% 8% 2 6% 5% 4 4 4 6% 6% 32%	1330
	11th to 20th	Night	21% 7% 2 6% 4 4 6% 5% 6% 6% 34%	1330
	21st to end	Night	27% 8% 4 7% 4 3 3 3 5% 7% 29%	1330
July	1st to 10th	Night	18% 7% 2 5% 4 4 4 4 6% 9% 37%	2210
	11th to 20th	Night	16% 8% 3 6% 5% 6% 5% 4 7% 8% 34%	2210
	21st to end	Night	13% 4 2 5% 4 3 5% 4 7% 8% 45%	2415
August	1st to 10th	Night	18% 8% 3 7% 4 4 4 5% 6% 7% 34%	2664
	11th to 20th	Night	18% 8% 3 9% 6% 5% 5% 5% 6% 7% 28%	2782
	21st to end	Night	15% 6% 3 6% 4 5% 5% 4 6% 6% 41%	3124
September	1st to 10th	Night	22% 7% 2 5% 4 4 4 3 5% 5% 39%	1827
	11th to 20th	Night	22% 6% 3 4 4 3 4 3 4 6% 41%	2090
	21st to end	Night	21% 6% 2 5% 4 3 3 3 5% 6% 42%	2090
October	1st to 10th	Night	23% 7% 3 7% 4 4 3 3 4 6% 37%	2251
	11th to 20th	Night	27% 8% 3 7% 4 3 4 4 4 5% 30%	2304
	21st to end	Night	26% 9% 3 7% 4 4 5% 3 4 5% 31%	2717
November	1st to 10th	Night	24% 10% 3 7% 4 4 4 3 5% 5% 31%	2723
	11th to 20th	Night	22% 13% 3 7% 5% 4 4 4 4 5% 29%	2800
	21st to end	Night	21% 16% 5% 8% 5% 3 3 3 5% 5% 26%	2914
December	1st to 10th	Night	19% 15% 3 7% 4 3 3 3 5% 6% 31%	2932
	11th to 20th	Night	22% 13% 4 7% 3 3 3 2 3 5% 35%	3531
	21st to end	Night	13% 12% 5% 10% 6% 6% 4 5% 5% 5% 31%	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	29% 36% 4 21% 9%	2208
	11th to 20th	Day	34% 40% 5% 19% 2	2210
	21st to end	Day	25% 42% 7% 8% 16% 2	2724
February	1st to 10th	Day	17% 64% 4 8% 5% 2	1634
	11th to 20th	Day	18% 64% 4 9% 5%	1671
	21st to end	Day	19% 65% 2 10% 4 1	1470
March	1st to 10th	Day	31% 43% 4 14% 7% 1	3210
	11th to 20th	Day	46% 41% 3 6% 3 1	3480
	21st to end	Day	38% 41% 4 9% 4 3	3816
April	1st to 10th	Day	17% 65% 2 7% 7% 1	2331
	11th to 20th	Day	18% 66% 3 7% 5% 1	2442
	21st to end	Day	22% 65% 4 6% 3 1	2470
May	1st to 10th	Day	32% 42% 7% 15% 3	4280
	11th to 20th	Day	32% 42% 8% 12% 5%	4645
	21st to end	Day	39% 42% 6% 9% 4	5185
June	1st to 10th	Day	20% 65% 3 8% 3	2850
	11th to 20th	Day	17% 66% 4 8% 4	2850
	21st to end	Day	18% 64% 5% 9% 3	2850
July	1st to 10th	Day	26% 38% 8% 21% 7%	4685
	11th to 20th	Day	30% 39% 12% 13% 6%	4679
	21st to end	Day	21% 38% 13% 21% 6% 1	4981
August	1st to 10th	Day	27% 41% 13% 15% 4	4219
	11th to 20th	Day	37% 41% 12% 8% 3	4084
	21st to end	Day	21% 39% 14% 18% 8%	4532
September	1st to 10th	Day	18% 61% 7% 11% 3	2351
	11th to 20th	Day	22% 61% 5% 10% 3	2090
	21st to end	Day	14% 60% 7% 12% 7%	2090
October	1st to 10th	Day	34% 38% 8% 15% 3 1	3201
	11th to 20th	Day	29% 39% 9% 18% 4	3091
	21st to end	Day	28% 39% 12% 13% 9%	3081
November	1st to 10th	Day	26% 56% 6% 6% 6%	1575
	11th to 20th	Day	27% 57% 4 8% 4	1600
	21st to end	Day	27% 57% 5% 8% 4	1485
December	1st to 10th	Day	22% 58% 6% 10% 2	1365
	11th to 20th	Day	28% 48% 3 13% 8% 1	1668
	21st to end	Day	27% 37% 8% 15% 8% 5%	2431
January	1st to 10th	Night	35% 37% 5% 12% 9% 1	4748
	11th to 20th	Night	35% 40% 6% 15% 3	4760
	21st to end	Night	22% 41% 11% 13% 12% 1	4918
February	1st to 10th	Night	16% 65% 2 8% 7% 2	2545
	11th to 20th	Night	20% 64% 2 8% 5%	2406
	21st to end	Night	19% 65% 2 6% 7% 1	1979
March	1st to 10th	Night	31% 42% 7% 10% 10%	3643
	11th to 20th	Night	47% 40% 2 7% 3	3480
	21st to end	Night	42% 40% 2 8% 6% 2	3816
April	1st to 10th	Night	17% 65% 1 7% 7% 2	1844
	11th to 20th	Night	19% 65% 2 6% 6% 2	1688
	21st to end	Night	23% 64% 2 5% 5%	1710
May	1st to 10th	Night	40% 42% 5% 11% 2	2685
	11th to 20th	Night	32% 43% 7% 13% 5%	2293
	21st to end	Night	39% 42% 4 12% 2	2402
June	1st to 10th	Night	17% 65% 3 10% 6%	1330
	11th to 20th	Night	19% 65% 3 8% 5%	1330
	21st to end	Night	17% 64% 5% 9% 4	1330
July	1st to 10th	Night	25% 39% 9% 19% 7%	2175
	11th to 20th	Night	29% 39% 10% 13% 9%	2168
	21st to end	Night	18% 39% 13% 19% 10% 2	2338
August	1st to 10th	Night	29% 40% 13% 16% 3	2654
	11th to 20th	Night	34% 41% 13% 10% 1	2809
	21st to end	Night	22% 41% 8% 20% 8%	3124
September	1st to 10th	Night	17% 60% 5% 13% 5% 1	1827
	11th to 20th	Night	22% 60% 6% 9% 3	2090
	21st to end	Night	16% 60% 5% 13% 6%	2090
October	1st to 10th	Night	34% 38% 6% 18% 4	3758
	11th to 20th	Night	33% 39% 10% 13% 5%	3827
	21st to end	Night	35% 40% 6% 16% 4	4467
November	1st to 10th	Night	25% 56% 6% 8% 5%	2723
	11th to 20th	Night	25% 57% 5% 9% 3	2800
	21st to end	Night	29% 57% 5% 6% 4	2914
December	1st to 10th	Night	22% 58% 5% 11% 4	2932
	11th to 20th	Night	28% 49% 3 13% 7%	3532
	21st to end	Night	32% 39% 7% 10% 7% 4	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	23% 9% 29% 22% 15% 2	180
	11th to 20th	Day	20% 11% 28% 24% 14% 2	180
	21st to end	Day	17% 14% 26% 27% 12% 4	198
February	1st to 10th	Day	13% 13% 35% 27% 9% 3	294
	11th to 20th	Day	14% 13% 39% 27% 7% 1	366
	21st to end	Day	19% 10% 36% 25% 8% 2	334
March	1st to 10th	Day	21% 14% 29% 26% 8% 2	460
	11th to 20th	Day	25% 10% 29% 25% 9% 2	460
	21st to end	Day	26% 16% 29% 21% 6% 1	506
April	1st to 10th	Day	25% 17% 28% 22% 6% 1	460
	11th to 20th	Day	24% 11% 34% 21% 9% 2	452
	21st to end	Day	31% 12% 29% 18% 8% 2	460
May	1st to 10th	Day	28% 9% 27% 25% 9% 2	558
	11th to 20th	Day	26% 10% 28% 21% 12% 2	674
	21st to end	Day	30% 14% 27% 21% 7% 1	735
June	1st to 10th	Day	30% 8% 29% 22% 9% 1	680
	11th to 20th	Day	26% 13% 26% 22% 11% 3	680
	21st to end	Day	30% 10% 27% 24% 8% 2	680
July	1st to 10th	Day	24% 11% 26% 25% 11% 3	670
	11th to 20th	Day	22% 9% 28% 29% 11% 2	668
	21st to end	Day	24% 7% 24% 29% 14% 2	735
August	1st to 10th	Day	24% 6% 27% 30% 9% 4	486
	11th to 20th	Day	24% 7% 28% 27% 11% 3	479
	21st to end	Day	20% 9% 29% 26% 13% 3	539
September	1st to 10th	Day	25% 13% 29% 21% 10% 2	490
	11th to 20th	Day	29% 8% 31% 21% 8% 3	490
	21st to end	Day	25% 14% 27% 21% 9% 3	490
October	1st to 10th	Day	24% 15% 29% 20% 10% 2	404
	11th to 20th	Day	32% 12% 25% 18% 11% 3	390
	21st to end	Day	34% 11% 24% 19% 10% 2	429
November	1st to 10th	Day	30% 16% 29% 19% 6% 1	395
	11th to 20th	Day	31% 10% 29% 20% 9% 2	400
	21st to end	Day	28% 19% 28% 18% 7%	285
December	1st to 10th	Day	21% 8% 24% 30% 14% 4	190
	11th to 20th	Day	18% 20% 31% 21% 8% 1	180
	21st to end	Day	24% 20% 25% 24% 6% 2	198
January	1st to 10th	Night	20% 7% 33% 29% 10%	850
	11th to 20th	Night	22% 10% 30% 30% 7%	850
	21st to end	Night	15% 10% 32% 34% 8% 1	845
February	1st to 10th	Night	13% 13% 36% 28% 10% 1	760
	11th to 20th	Night	20% 12% 31% 26% 9% 1	743
	21st to end	Night	18% 11% 32% 27% 9% 3	628
March	1st to 10th	Night	19% 11% 29% 31% 9% 1	760
	11th to 20th	Night	20% 12% 28% 29% 10%	760
	21st to end	Night	23% 11% 31% 26% 8% 1	836
April	1st to 10th	Night	27% 10% 28% 26% 7%	646
	11th to 20th	Night	24% 11% 28% 28% 9% 1	564
	21st to end	Night	30% 8% 24% 28% 9% 1	570
May	1st to 10th	Night	30% 6% 24% 31% 7% 1	570
	11th to 20th	Night	24% 7% 22% 34% 12% 1	439
	21st to end	Night	26% 9% 27% 31% 7%	411
June	1st to 10th	Night	27% 5% 23% 35% 9%	380
	11th to 20th	Night	26% 2 21% 33% 17% 1	380
	21st to end	Night	28% 5% 22% 34% 9% 2	380
July	1st to 10th	Night	26% 4 23% 32% 15% 1	370
	11th to 20th	Night	23% 4 16% 40% 15% 1	368
	21st to end	Night	20% 5% 16% 40% 18% 1	416
August	1st to 10th	Night	24% 2 17% 35% 20% 1	471
	11th to 20th	Night	22% 4 18% 39% 17% 1	562
	21st to end	Night	20% 6% 19% 37% 16% 2	627
September	1st to 10th	Night	25% 5% 24% 33% 12% 1	573
	11th to 20th	Night	26% 5% 24% 31% 13% 2	760
	21st to end	Night	25% 8% 25% 31% 11% 1	760
October	1st to 10th	Night	28% 9% 28% 25% 9% 1	760
	11th to 20th	Night	30% 7% 25% 23% 14% 1	760
	21st to end	Night	31% 7% 26% 27% 8% 1	836
November	1st to 10th	Night	30% 10% 29% 25% 5%	875
	11th to 20th	Night	27% 11% 28% 25% 8% 1	900
	21st to end	Night	29% 9% 29% 25% 8%	900
December	1st to 10th	Night	26% 10% 26% 27% 10% 1	878
	11th to 20th	Night	24% 13% 32% 23% 6%	850
	21st to end	Night	23% 10% 33% 24% 8% 1	935

Page generated at 2024-12-03 06:45:11. Version ac07

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