Porteau Cove Provincial Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Porteau Cove Provincial Park clear sky chart from 2005-11-06 to 2024-12-09.

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	24% 11% 3 7% 4 4 4 3 4 5% 32%	105777
	Night	28% 13% 3 6% 4 3 3 3 4 5% 29%	102583
Transparency	Day	57% 7% 11% 16% 8% 2	105524
	Night	60% 6% 10% 14% 8% 2	102482
Seeing	Day	27% 12% 25% 23% 10% 2	15514
	Night	34% 7% 21% 23% 14% 2	23675

By Month

Percentage Cloud Cover NW (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	38% 20% 3 6% 3 3 3 3 3 3 14%	2219
	11th to 20th	Day	27% 14% 5% 8% 4 3 2 1 2 4 29%	2199
	21st to end	Day	53% 17% 2 4 2 2 2 1 2 2 12%	2732
February	1st to 10th	Day	31% 16% 4 7% 5% 3 3 3 5% 5% 17%	1710
	11th to 20th	Day	26% 19% 4 8% 4 3 2 2 4 5% 23%	1665
	21st to end	Day	21% 20% 5% 9% 6% 4 5% 3 4 3 19%	1415
March	1st to 10th	Day	24% 22% 5% 9% 5% 4 4 2 4 4 18%	3257
	11th to 20th	Day	24% 15% 4 7% 4 4 3 2 4 4 30%	3490
	21st to end	Day	26% 18% 4 10% 6% 4 4 2 3 4 19%	3912
April	1st to 10th	Day	27% 18% 4 9% 7% 5% 4 3 5% 4 15%	2280
	11th to 20th	Day	24% 15% 4 10% 6% 5% 4 3 4 5% 21%	2365
	21st to end	Day	28% 13% 3 7% 5% 5% 5% 3 5% 4 20%	2523
May	1st to 10th	Day	16% 12% 3 8% 5% 4 4 3 4 5% 36%	4420
	11th to 20th	Day	14% 9% 3 7% 5% 4 5% 5% 8% 10% 31%	4377
	21st to end	Day	29% 12% 3 8% 5% 4 5% 4 5% 6% 20%	4973
June	1st to 10th	Day	27% 10% 3 7% 5% 4 4 3 5% 5% 24%	2850
	11th to 20th	Day	25% 12% 4 10% 6% 6% 4 3 4 5% 21%	2850
	21st to end	Day	20% 9% 3 7% 5% 5% 4 3 5% 6% 33%	2850
July	1st to 10th	Day	8% 5% 1 4 3 2 3 2 3 4 64%	4740
	11th to 20th	Day	7% 3 1 3 2 2 3 2 4 5% 67%	4740
	21st to end	Day	13% 6% 2 5% 3 3 3 3 5% 7% 49%	4931
August	1st to 10th	Day	7% 3 1 4 2 2 2 2 4 7% 65%	4357
	11th to 20th	Day	16% 8% 3 8% 4 4 3 3 4 6% 42%	4026
	21st to end	Day	18% 7% 2 6% 4 3 4 3 6% 7% 40%	4440
September	1st to 10th	Day	15% 6% 2 5% 3 5% 4 3 5% 6% 46%	2280
	11th to 20th	Day	22% 8% 3 6% 3 4 4 3 4 5% 38%	2266
	21st to end	Day	27% 8% 2 6% 4 4 4 3 3 6% 34%	2007
October	1st to 10th	Day	27% 9% 3 7% 4 5% 4 3 4 6% 28%	3180
	11th to 20th	Day	36% 9% 2 7% 4 4 4 4 4 6% 21%	3161
	21st to end	Day	31% 12% 4 9% 4 4 5% 4 5% 6% 16%	3150
November	1st to 10th	Day	41% 10% 3 7% 5% 4 3 3 4 3 17%	1568
	11th to 20th	Day	39% 16% 4 6% 2 2 3 2 3 3 20%	1600
	21st to end	Day	37% 15% 3 6% 4 4 4 2 3 3 20%	1600
December	1st to 10th	Day	30% 16% 3 6% 4 4 3 2 3 4 26%	1517
	11th to 20th	Day	40% 16% 4 6% 4 2 2 2 3 3 17%	1685
	21st to end	Day	40% 18% 4 8% 4 3 3 2 2 3 13%	2442
January	1st to 10th	Night	37% 20% 4 8% 4 3 2 2 3 3 15%	4726
	11th to 20th	Night	30% 12% 3 5% 4 3 3 3 4 7% 24%	4699
	21st to end	Night	51% 17% 3 5% 3 2 2 1 2 3 12%	4921
February	1st to 10th	Night	32% 13% 4 8% 4 4 4 3 4 4 19%	2470
	11th to 20th	Night	25% 18% 4 7% 5% 4 4 2 3 4 24%	2402
	21st to end	Night	27% 18% 3 7% 4 4 3 3 3 4 24%	2038
March	1st to 10th	Night	25% 22% 4 7% 4 3 3 3 5% 4 20%	3615
	11th to 20th	Night	24% 17% 3 6% 3 3 3 2 4 4 31%	3489
	21st to end	Night	30% 19% 4 6% 4 3 3 2 4 3 21%	3741
April	1st to 10th	Night	28% 15% 4 7% 5% 5% 4 3 4 4 20%	1900
	11th to 20th	Night	23% 15% 3 6% 5% 4 4 3 4 6% 27%	1762
	21st to end	Night	27% 13% 3 8% 4 3 4 3 5% 5% 25%	1655
May	1st to 10th	Night	17% 11% 3 6% 3 3 3 3 4 4 44%	2540
	11th to 20th	Night	14% 7% 3 5% 4 4 4 3 7% 10% 39%	2516
	21st to end	Night	26% 15% 4 7% 5% 4 4 3 4 5% 23%	2585
June	1st to 10th	Night	25% 9% 3 7% 4 4 3 3 4 5% 30%	1330
	11th to 20th	Night	21% 13% 4 8% 5% 5% 5% 3 5% 5% 26%	1330
	21st to end	Night	16% 9% 3 7% 4 4 4 3 5% 7% 37%	1330
July	1st to 10th	Night	6% 5% 1 3 2 2 3 3 4 5% 66%	2220
	11th to 20th	Night	6% 3 1 2 2 2 2 2 3 5% 72%	2220
	21st to end	Night	13% 6% 2 4 2 2 4 4 5% 5% 53%	2621
August	1st to 10th	Night	6% 3 1 2 2 1 2 2 4 5% 73%	2560
	11th to 20th	Night	16% 6% 2 7% 3 4 3 4 5% 6% 44%	2812
	21st to end	Night	17% 6% 2 6% 5% 4 4 3 5% 6% 42%	3230
September	1st to 10th	Night	11% 5% 2 6% 4 3 3 3 4 6% 54%	1900
	11th to 20th	Night	22% 7% 2 6% 4 3 3 4 3 5% 40%	1910
	21st to end	Night	25% 11% 2 5% 3 3 3 3 4 6% 34%	2172
October	1st to 10th	Night	24% 12% 3 7% 5% 4 4 3 4 5% 28%	3800
	11th to 20th	Night	34% 10% 3 5% 3 4 3 2 3 5% 27%	3777
	21st to end	Night	33% 12% 4 7% 4 3 4 3 3 4 22%	4407
November	1st to 10th	Night	41% 13% 3 7% 4 3 3 3 3 4 17%	2730
	11th to 20th	Night	38% 14% 4 6% 4 3 3 2 3 3 20%	2800
	21st to end	Night	36% 13% 3 8% 4 4 3 2 3 4 21%	2800
December	1st to 10th	Night	30% 14% 4 7% 4 3 3 2 4 4 25%	2841
	11th to 20th	Night	42% 18% 4 6% 4 2 3 2 3 3 13%	3520
	21st to end	Night	43% 19% 4 6% 3 2 2 1 2 3 15%	5214

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	77% 4 7% 7% 3 2	2219
	11th to 20th	Day	64% 3 7% 12% 9% 5%	2220
	21st to end	Day	84% 2 5% 7% 2 1	2732
February	1st to 10th	Day	73% 4 7% 8% 5% 3	1710
	11th to 20th	Day	66% 5% 8% 12% 7% 2	1674
	21st to end	Day	72% 5% 7% 9% 4 3	1415
March	1st to 10th	Day	70% 7% 8% 9% 6%	3257
	11th to 20th	Day	60% 5% 7% 20% 8% 1	3490
	21st to end	Day	72% 6% 9% 9% 3 1	3912
April	1st to 10th	Day	74% 7% 9% 8% 2	2280
	11th to 20th	Day	68% 8% 6% 10% 8% 1	2365
	21st to end	Day	72% 7% 6% 9% 6%	2523
May	1st to 10th	Day	51% 12% 11% 17% 9%	4420
	11th to 20th	Day	48% 10% 19% 19% 4	4380
	21st to end	Day	66% 10% 11% 11% 2	4974
June	1st to 10th	Day	64% 7% 12% 10% 4 2	2850
	11th to 20th	Day	69% 7% 11% 9% 4	2850
	21st to end	Day	55% 6% 13% 17% 7% 2	2850
July	1st to 10th	Day	27% 5% 11% 25% 22% 11%	4666
	11th to 20th	Day	22% 4 12% 37% 22% 2	4659
	21st to end	Day	32% 10% 21% 22% 13% 2	4775
August	1st to 10th	Day	23% 4 11% 44% 17% 1	4340
	11th to 20th	Day	44% 9% 20% 17% 8% 2	4065
	21st to end	Day	44% 7% 18% 20% 9% 1	4439
September	1st to 10th	Day	42% 6% 13% 24% 12% 4	2280
	11th to 20th	Day	51% 5% 10% 18% 15% 2	2266
	21st to end	Day	55% 5% 13% 16% 9% 2	2007
October	1st to 10th	Day	59% 9% 12% 15% 6%	3180
	11th to 20th	Day	66% 7% 10% 11% 5%	3161
	21st to end	Day	69% 10% 9% 7% 4 1	3150
November	1st to 10th	Day	74% 5% 8% 8% 5% 1	1568
	11th to 20th	Day	73% 5% 6% 7% 7% 3	1600
	21st to end	Day	73% 4 4 9% 8% 2	1600
December	1st to 10th	Day	65% 6% 8% 10% 9% 2	1517
	11th to 20th	Day	76% 4 7% 7% 3 2	1688
	21st to end	Day	81% 4 5% 6% 4 1	2442
January	1st to 10th	Night	78% 4 4 9% 4 1	4726
	11th to 20th	Night	61% 6% 8% 12% 10% 3	4740
	21st to end	Night	82% 3 4 7% 4 1	4921
February	1st to 10th	Night	70% 5% 7% 10% 6% 2	2470
	11th to 20th	Night	67% 5% 8% 11% 7% 2	2404
	21st to end	Night	65% 6% 8% 13% 7% 2	2038
March	1st to 10th	Night	66% 5% 8% 11% 8% 1	3615
	11th to 20th	Night	57% 7% 9% 17% 10% 1	3490
	21st to end	Night	71% 5% 11% 9% 4 1	3741
April	1st to 10th	Night	69% 7% 11% 12% 2	1900
	11th to 20th	Night	61% 7% 8% 14% 8% 2	1762
	21st to end	Night	64% 5% 12% 12% 7%	1655
May	1st to 10th	Night	43% 8% 14% 25% 9%	2540
	11th to 20th	Night	38% 14% 23% 20% 5%	2516
	21st to end	Night	62% 10% 14% 11% 3	2585
June	1st to 10th	Night	56% 7% 16% 13% 5% 3	1330
	11th to 20th	Night	60% 8% 15% 12% 5%	1330
	21st to end	Night	49% 9% 16% 16% 8% 3	1330
July	1st to 10th	Night	23% 5% 13% 26% 23% 11%	2185
	11th to 20th	Night	18% 4 12% 36% 28% 2	2178
	21st to end	Night	32% 6% 16% 26% 14% 5%	2538
August	1st to 10th	Night	17% 4 14% 36% 28% 2	2552
	11th to 20th	Night	40% 10% 22% 15% 9% 4	2839
	21st to end	Night	43% 7% 20% 20% 9% 1	3230
September	1st to 10th	Night	33% 8% 16% 25% 14% 5%	1900
	11th to 20th	Night	48% 6% 11% 16% 14% 5%	1910
	21st to end	Night	53% 5% 13% 18% 8% 2	2172
October	1st to 10th	Night	59% 7% 14% 12% 7% 1	3800
	11th to 20th	Night	63% 6% 8% 15% 8%	3777
	21st to end	Night	65% 8% 8% 12% 6% 1	4407
November	1st to 10th	Night	74% 5% 7% 8% 5% 2	2730
	11th to 20th	Night	73% 4 6% 8% 6% 3	2800
	21st to end	Night	71% 4 6% 8% 9% 2	2800
December	1st to 10th	Night	65% 5% 9% 11% 8% 3	2841
	11th to 20th	Night	79% 4 6% 5% 4 2	3516
	21st to end	Night	79% 3 4 8% 5% 1	5214

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	48% 8% 17% 16% 7% 4	180
	11th to 20th	Day	44% 13% 16% 17% 9% 2	180
	21st to end	Day	50% 9% 18% 17% 6%	219
February	1st to 10th	Day	43% 9% 28% 16% 5%	370
	11th to 20th	Day	37% 13% 26% 18% 5% 1	365
	21st to end	Day	31% 17% 29% 15% 7% 1	309
March	1st to 10th	Day	33% 17% 24% 19% 6% 1	460
	11th to 20th	Day	35% 15% 20% 19% 10% 1	460
	21st to end	Day	37% 16% 26% 15% 6% 1	506
April	1st to 10th	Day	37% 18% 21% 16% 7% 1	460
	11th to 20th	Day	29% 19% 25% 19% 6% 2	452
	21st to end	Day	30% 18% 28% 15% 8% 1	460
May	1st to 10th	Day	21% 16% 30% 25% 8% 1	463
	11th to 20th	Day	21% 12% 27% 27% 11% 2	488
	21st to end	Day	24% 14% 28% 24% 9% 2	624
June	1st to 10th	Day	27% 14% 26% 24% 7% 1	680
	11th to 20th	Day	24% 17% 33% 18% 7% 1	680
	21st to end	Day	17% 13% 29% 28% 12% 2	680
July	1st to 10th	Day	18% 10% 25% 35% 11% 2	671
	11th to 20th	Day	10% 10% 29% 36% 12% 3	668
	21st to end	Day	9% 9% 25% 37% 16% 4	620
August	1st to 10th	Day	12% 6% 23% 34% 17% 8%	487
	11th to 20th	Day	10% 7% 24% 39% 17% 4	477
	21st to end	Day	17% 10% 28% 29% 12% 3	539
September	1st to 10th	Day	18% 11% 29% 27% 14% 2	490
	11th to 20th	Day	27% 12% 22% 24% 12% 2	490
	21st to end	Day	30% 11% 25% 20% 11% 3	490
October	1st to 10th	Day	32% 9% 22% 21% 13% 3	490
	11th to 20th	Day	43% 7% 18% 18% 10% 4	490
	21st to end	Day	40% 12% 22% 15% 8% 3	392
November	1st to 10th	Day	38% 16% 24% 16% 7%	200
	11th to 20th	Day	46% 8% 17% 12% 13% 6%	200
	21st to end	Day	46% 14% 18% 10% 5% 9%	200
December	1st to 10th	Day	45% 7% 16% 15% 14% 4	196
	11th to 20th	Day	44% 10% 18% 18% 8% 2	180
	21st to end	Day	43% 7% 31% 14% 5%	198
January	1st to 10th	Night	49% 10% 19% 15% 6% 1	850
	11th to 20th	Night	43% 6% 23% 20% 7%	850
	21st to end	Night	45% 7% 21% 21% 7%	861
February	1st to 10th	Night	38% 8% 27% 21% 6%	760
	11th to 20th	Night	36% 8% 29% 21% 6%	744
	21st to end	Night	36% 11% 22% 21% 10% 1	628
March	1st to 10th	Night	36% 10% 23% 19% 11% 1	760
	11th to 20th	Night	41% 9% 19% 22% 9%	760
	21st to end	Night	41% 7% 19% 21% 11% 1	836
April	1st to 10th	Night	35% 7% 21% 26% 10% 1	760
	11th to 20th	Night	29% 8% 27% 25% 10% 1	634
	21st to end	Night	33% 5% 26% 24% 11%	515
May	1st to 10th	Night	19% 3 24% 34% 19% 2	380
	11th to 20th	Night	20% 4 18% 31% 25% 2	374
	21st to end	Night	21% 4 20% 33% 20% 2	411
June	1st to 10th	Night	27% 4 17% 31% 18% 2	380
	11th to 20th	Night	22% 9% 22% 28% 18% 2	380
	21st to end	Night	16% 6% 19% 31% 27% 2	380
July	1st to 10th	Night	13% 1 17% 30% 36% 4	370
	11th to 20th	Night	11% 2 10% 35% 38% 4	368
	21st to end	Night	10% 2 9% 30% 42% 7%	416
August	1st to 10th	Night	11% 2 6% 29% 42% 9%	396
	11th to 20th	Night	10% 2 9% 33% 41% 6%	564
	21st to end	Night	16% 4 16% 32% 30% 3	672
September	1st to 10th	Night	13% 4 17% 36% 28% 3	760
	11th to 20th	Night	25% 3 16% 24% 27% 5%	760
	21st to end	Night	32% 5% 17% 27% 18% 1	760
October	1st to 10th	Night	27% 7% 19% 27% 19% 1	760
	11th to 20th	Night	39% 6% 19% 22% 14% 2	760
	21st to end	Night	42% 8% 24% 19% 6% 1	836
November	1st to 10th	Night	46% 10% 23% 19% 2	780
	11th to 20th	Night	45% 8% 25% 15% 6% 1	800
	21st to end	Night	43% 9% 23% 18% 7% 2	800
December	1st to 10th	Night	37% 7% 27% 23% 7%	825
	11th to 20th	Night	51% 8% 24% 15% 2	850
	21st to end	Night	48% 11% 26% 14% 1	935

Page generated at 2024-12-06 00:54:51. Version ac07

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