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 2024-01-16.

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	26% 11% 4 6% 5% 3 4 4 4 5% 29%	74754
	Night	29% 12% 3 5% 5% 2 3 3 4 5% 28%	75065
Transparency	Day	61% 6% 10% 15% 7% 2	74441
	Night	62% 5% 10% 14% 7% 2	74896
Seeing	Day	28% 12% 25% 23% 10% 2	14288
	Night	34% 6% 21% 23% 14% 2	22596

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	45% 14% 4 5% 4 2 3 3 2 3 15%	1329
	11th to 20th	Day	35% 11% 5% 8% 6% 2 3 2 3 4 20%	1295
	21st to end	Day	33% 19% 4 5% 4 3 3 3 3 4 19%	1550
February	1st to 10th	Day	32% 15% 4 6% 5% 3 3 4 5% 6% 17%	1620
	11th to 20th	Day	28% 18% 4 6% 4 2 2 3 4 5% 23%	1575
	21st to end	Day	21% 18% 6% 8% 6% 3 5% 4 4 4 20%	1333
March	1st to 10th	Day	29% 16% 4 8% 6% 3 4 3 3 3 20%	1867
	11th to 20th	Day	35% 18% 4 6% 5% 3 4 2 3 3 16%	1980
	21st to end	Day	31% 16% 4 9% 7% 3 3 3 3 3 17%	2227
April	1st to 10th	Day	28% 16% 5% 7% 8% 4 5% 4 5% 4 16%	2160
	11th to 20th	Day	26% 13% 5% 9% 7% 3 5% 3 3 5% 19%	2238
	21st to end	Day	28% 12% 4 7% 6% 4 6% 4 4 4 21%	2390
May	1st to 10th	Day	20% 10% 4 7% 7% 4 5% 5% 4 6% 28%	2520
	11th to 20th	Day	19% 9% 4 7% 7% 4 5% 5% 6% 7% 27%	2477
	21st to end	Day	23% 9% 4 7% 6% 4 5% 4 5% 6% 27%	2813
June	1st to 10th	Day	27% 10% 4 7% 6% 3 4 4 5% 5% 25%	2700
	11th to 20th	Day	26% 10% 4 10% 7% 4 6% 3 4 5% 20%	2700
	21st to end	Day	20% 8% 3 6% 5% 4 5% 3 5% 6% 34%	2700
July	1st to 10th	Day	14% 7% 2 6% 5% 3 4 4 4 5% 45%	2700
	11th to 20th	Day	13% 5% 2 4 4 3 4 5% 5% 7% 47%	2700
	21st to end	Day	10% 4 2 3 4 2 3 4 5% 7% 56%	2826
August	1st to 10th	Day	13% 5% 2 5% 4 2 3 4 3 6% 53%	2489
	11th to 20th	Day	10% 5% 2 4 4 3 3 3 4 5% 54%	2298
	21st to end	Day	14% 7% 2 6% 5% 2 4 5% 6% 8% 40%	2532
September	1st to 10th	Day	15% 6% 3 5% 4 3 4 4 5% 6% 45%	2160
	11th to 20th	Day	22% 7% 3 6% 4 3 4 4 4 4 39%	2147
	21st to end	Day	26% 7% 3 5% 4 3 4 4 3 6% 35%	1902
October	1st to 10th	Day	27% 9% 2 5% 4 2 4 4 3 5% 34%	1800
	11th to 20th	Day	36% 8% 2 5% 6% 3 4 4 4 6% 23%	1800
	21st to end	Day	37% 10% 3 4 4 2 3 4 3 6% 23%	1816
November	1st to 10th	Day	41% 9% 3 6% 6% 3 4 3 3 3 17%	1488
	11th to 20th	Day	41% 15% 3 5% 3 1 2 3 2 2 21%	1520
	21st to end	Day	39% 13% 3 4 5% 3 4 3 3 3 20%	1520
December	1st to 10th	Day	32% 15% 4 5% 3 3 3 3 3 4 25%	1455
	11th to 20th	Day	41% 15% 5% 5% 5% 2 3 2 4 3 17%	1685
	21st to end	Day	41% 17% 5% 7% 6% 2 3 2 1 3 13%	2442
January	1st to 10th	Night	43% 15% 3 6% 4 3 3 3 3 3 15%	2836
	11th to 20th	Night	37% 12% 4 5% 5% 2 3 3 4 6% 18%	2787
	21st to end	Night	32% 16% 4 6% 5% 2 3 3 3 5% 20%	2802
February	1st to 10th	Night	33% 13% 4 6% 5% 3 3 4 4 5% 20%	2340
	11th to 20th	Night	26% 18% 5% 6% 5% 3 3 3 3 4 23%	2272
	21st to end	Night	27% 16% 3 6% 5% 3 4 3 3 4 24%	1922
March	1st to 10th	Night	29% 17% 4 5% 5% 3 4 3 4 4 21%	2091
	11th to 20th	Night	35% 18% 3 6% 4 3 3 2 3 4 19%	1979
	21st to end	Night	34% 16% 3 5% 6% 3 4 3 4 3 18%	2129
April	1st to 10th	Night	29% 14% 5% 5% 6% 3 5% 4 4 5% 20%	1800
	11th to 20th	Night	24% 14% 4 6% 6% 3 4 4 4 6% 25%	1669
	21st to end	Night	27% 11% 4 7% 5% 3 4 4 5% 5% 26%	1568
May	1st to 10th	Night	17% 8% 3 5% 4 3 5% 5% 6% 6% 37%	1440
	11th to 20th	Night	18% 9% 3 6% 5% 4 5% 5% 7% 10% 28%	1416
	21st to end	Night	18% 9% 4 6% 6% 3 5% 5% 5% 6% 33%	1459
June	1st to 10th	Night	25% 9% 4 7% 5% 3 4 4 4 5% 30%	1260
	11th to 20th	Night	21% 13% 4 7% 5% 4 5% 4 5% 6% 25%	1260
	21st to end	Night	16% 7% 3 6% 6% 3 5% 5% 5% 7% 38%	1260
July	1st to 10th	Night	11% 7% 3 5% 4 2 4 4 5% 6% 50%	1260
	11th to 20th	Night	10% 5% 2 3 4 3 4 3 5% 8% 54%	1260
	21st to end	Night	8% 4 2 3 3 1 3 4 5% 6% 61%	1491
August	1st to 10th	Night	10% 5% 2 3 4 2 2 3 4 5% 60%	1449
	11th to 20th	Night	7% 4 1 4 3 2 3 5% 5% 7% 58%	1602
	21st to end	Night	13% 6% 2 5% 6% 3 4 4 6% 8% 43%	1824
September	1st to 10th	Night	12% 5% 2 5% 5% 2 3 4 4 6% 54%	1800
	11th to 20th	Night	22% 7% 2 5% 4 2 4 4 3 5% 41%	1809
	21st to end	Night	25% 10% 2 4 4 2 3 4 3 6% 35%	2057
October	1st to 10th	Night	24% 8% 3 5% 5% 2 4 4 3 5% 37%	2160
	11th to 20th	Night	34% 9% 3 4 4 2 4 3 3 5% 29%	2160
	21st to end	Night	37% 9% 3 6% 4 2 4 4 3 5% 24%	2538
November	1st to 10th	Night	42% 13% 3 6% 4 2 3 3 3 4 17%	2590
	11th to 20th	Night	38% 13% 4 5% 4 2 3 3 3 3 21%	2660
	21st to end	Night	38% 11% 3 6% 5% 3 3 2 2 3 22%	2660
December	1st to 10th	Night	31% 13% 4 6% 5% 2 3 4 4 4 24%	2721
	11th to 20th	Night	42% 17% 4 6% 4 2 3 3 3 3 13%	3520
	21st to end	Night	43% 18% 4 6% 4 2 2 2 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	78% 3 5% 8% 3 3	1329
	11th to 20th	Day	71% 4 7% 11% 4 3	1295
	21st to end	Day	73% 4 7% 11% 4 2	1550
February	1st to 10th	Day	73% 4 7% 8% 5% 3	1620
	11th to 20th	Day	67% 5% 8% 11% 7% 1	1584
	21st to end	Day	71% 5% 8% 10% 4 3	1333
March	1st to 10th	Day	71% 5% 8% 11% 4 1	1867
	11th to 20th	Day	77% 4 5% 9% 4 1	1980
	21st to end	Day	75% 4 8% 10% 3	2227
April	1st to 10th	Day	74% 6% 9% 8% 2	2160
	11th to 20th	Day	70% 7% 6% 10% 7%	2238
	21st to end	Day	72% 6% 6% 9% 6%	2390
May	1st to 10th	Day	61% 8% 11% 14% 5% 1	2520
	11th to 20th	Day	60% 8% 12% 17% 4 1	2480
	21st to end	Day	61% 8% 11% 16% 4	2814
June	1st to 10th	Day	65% 7% 12% 10% 4 3	2700
	11th to 20th	Day	70% 7% 10% 9% 4	2700
	21st to end	Day	54% 6% 14% 17% 7% 2	2700
July	1st to 10th	Day	45% 6% 13% 21% 12% 2	2626
	11th to 20th	Day	39% 7% 17% 26% 10%	2619
	21st to end	Day	29% 6% 16% 29% 15% 4	2669
August	1st to 10th	Day	37% 6% 15% 27% 13% 2	2472
	11th to 20th	Day	33% 6% 18% 26% 14% 3	2298
	21st to end	Day	44% 8% 16% 25% 6% 2	2532
September	1st to 10th	Day	43% 6% 12% 25% 10% 4	2160
	11th to 20th	Day	51% 4 9% 18% 15% 2	2147
	21st to end	Day	54% 5% 13% 17% 9% 2	1902
October	1st to 10th	Day	55% 6% 12% 17% 10%	1800
	11th to 20th	Day	63% 6% 11% 14% 5% 1	1800
	21st to end	Day	66% 4 10% 11% 7% 1	1816
November	1st to 10th	Day	74% 4 8% 8% 5% 1	1488
	11th to 20th	Day	73% 4 6% 7% 7% 3	1520
	21st to end	Day	73% 4 4 10% 8% 2	1520
December	1st to 10th	Day	66% 6% 7% 10% 9% 2	1455
	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% 3 3 10% 4 2	2836
	11th to 20th	Night	70% 4 9% 9% 6% 2	2787
	21st to end	Night	69% 4 7% 12% 6% 2	2802
February	1st to 10th	Night	70% 5% 7% 10% 6% 3	2340
	11th to 20th	Night	68% 5% 8% 11% 7% 2	2274
	21st to end	Night	65% 5% 8% 13% 7% 2	1922
March	1st to 10th	Night	67% 5% 9% 12% 5% 1	2091
	11th to 20th	Night	72% 5% 6% 11% 5% 1	1980
	21st to end	Night	71% 6% 11% 9% 3	2129
April	1st to 10th	Night	69% 6% 11% 12% 2	1800
	11th to 20th	Night	63% 6% 9% 14% 8% 1	1669
	21st to end	Night	63% 5% 12% 12% 7%	1568
May	1st to 10th	Night	48% 10% 18% 19% 6% 1	1440
	11th to 20th	Night	53% 8% 16% 17% 6%	1416
	21st to end	Night	53% 7% 17% 17% 5%	1459
June	1st to 10th	Night	57% 7% 16% 13% 4 3	1260
	11th to 20th	Night	60% 8% 15% 12% 4	1260
	21st to end	Night	47% 9% 17% 16% 8% 3	1260
July	1st to 10th	Night	37% 6% 18% 22% 15% 2	1225
	11th to 20th	Night	31% 7% 21% 29% 11% 1	1218
	21st to end	Night	23% 6% 15% 33% 19% 5%	1408
August	1st to 10th	Night	28% 6% 18% 26% 19% 3	1441
	11th to 20th	Night	26% 7% 22% 24% 14% 6%	1602
	21st to end	Night	40% 7% 17% 25% 9% 2	1824
September	1st to 10th	Night	34% 8% 16% 25% 14% 3	1800
	11th to 20th	Night	47% 6% 10% 16% 15% 6%	1809
	21st to end	Night	52% 5% 13% 18% 9% 2	2057
October	1st to 10th	Night	53% 5% 12% 17% 12% 1	2160
	11th to 20th	Night	62% 5% 10% 16% 7%	2160
	21st to end	Night	64% 6% 7% 13% 9% 1	2538
November	1st to 10th	Night	75% 4 7% 8% 5% 2	2590
	11th to 20th	Night	72% 4 7% 9% 6% 3	2660
	21st to end	Night	71% 3 6% 9% 9% 2	2660
December	1st to 10th	Night	66% 5% 8% 10% 8% 3	2721
	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% 16% 9% 2	170
	21st to end	Day	46% 9% 19% 19% 7% 1	196
February	1st to 10th	Day	44% 9% 28% 14% 4	340
	11th to 20th	Day	38% 13% 26% 16% 5% 1	335
	21st to end	Day	29% 17% 30% 16% 7% 1	281
March	1st to 10th	Day	34% 17% 25% 19% 5%	420
	11th to 20th	Day	37% 15% 20% 18% 9% 1	420
	21st to end	Day	38% 15% 26% 15% 5% 1	462
April	1st to 10th	Day	38% 18% 20% 16% 7% 1	420
	11th to 20th	Day	31% 18% 23% 19% 7% 2	412
	21st to end	Day	30% 18% 28% 15% 7% 1	420
May	1st to 10th	Day	21% 16% 31% 24% 7% 1	423
	11th to 20th	Day	22% 11% 26% 28% 11% 2	448
	21st to end	Day	22% 13% 29% 25% 9% 2	575
June	1st to 10th	Day	26% 14% 26% 25% 7% 1	630
	11th to 20th	Day	25% 17% 33% 18% 7% 1	630
	21st to end	Day	17% 11% 30% 28% 12% 2	630
July	1st to 10th	Day	19% 9% 24% 35% 11% 2	621
	11th to 20th	Day	11% 10% 31% 35% 11% 2	618
	21st to end	Day	8% 8% 26% 38% 16% 4	572
August	1st to 10th	Day	13% 6% 24% 32% 17% 8%	447
	11th to 20th	Day	8% 6% 23% 40% 17% 4	437
	21st to end	Day	17% 10% 28% 30% 11% 4	495
September	1st to 10th	Day	18% 12% 31% 27% 11% 1	450
	11th to 20th	Day	27% 13% 21% 24% 13% 2	450
	21st to end	Day	29% 10% 23% 22% 12% 4	450
October	1st to 10th	Day	32% 8% 22% 20% 14% 3	450
	11th to 20th	Day	42% 8% 17% 18% 11% 4	450
	21st to end	Day	42% 11% 22% 14% 8% 3	358
November	1st to 10th	Day	37% 15% 23% 17% 8%	180
	11th to 20th	Day	46% 7% 15% 12% 13% 6%	180
	21st to end	Day	47% 13% 17% 9% 4 9%	180
December	1st to 10th	Day	48% 6% 16% 13% 13% 4	180
	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% 8%	829
	21st to end	Night	42% 7% 22% 22% 7%	814
February	1st to 10th	Night	39% 8% 27% 21% 5%	720
	11th to 20th	Night	36% 8% 29% 21% 6%	704
	21st to end	Night	35% 11% 22% 21% 10% 1	592
March	1st to 10th	Night	37% 9% 23% 19% 11% 1	720
	11th to 20th	Night	43% 9% 19% 20% 9%	720
	21st to end	Night	42% 6% 19% 22% 10% 1	792
April	1st to 10th	Night	36% 6% 20% 25% 11% 2	720
	11th to 20th	Night	30% 7% 27% 24% 10% 1	601
	21st to end	Night	33% 5% 26% 25% 11%	488
May	1st to 10th	Night	19% 3 23% 34% 19% 2	360
	11th to 20th	Night	21% 4 17% 30% 26% 3	354
	21st to end	Night	20% 4 19% 34% 21% 2	389
June	1st to 10th	Night	27% 4 17% 30% 19% 2	360
	11th to 20th	Night	22% 9% 22% 28% 18% 2	360
	21st to end	Night	16% 5% 19% 31% 28% 2	360
July	1st to 10th	Night	13% 1 15% 29% 37% 4	350
	11th to 20th	Night	12% 2 10% 34% 37% 5%	348
	21st to end	Night	9% 2 9% 30% 43% 8%	394
August	1st to 10th	Night	12% 2 6% 28% 42% 10%	375
	11th to 20th	Night	9% 2 9% 34% 41% 6%	534
	21st to end	Night	16% 3 15% 32% 31% 3	636
September	1st to 10th	Night	13% 3 18% 35% 28% 3	720
	11th to 20th	Night	26% 3 16% 23% 27% 5%	720
	21st to end	Night	32% 4 16% 28% 19% 1	720
October	1st to 10th	Night	28% 6% 19% 27% 19% 1	720
	11th to 20th	Night	39% 5% 18% 22% 14% 2	720
	21st to end	Night	42% 7% 23% 20% 6% 1	792
November	1st to 10th	Night	47% 9% 22% 19% 3	740
	11th to 20th	Night	44% 8% 26% 16% 6% 1	760
	21st to end	Night	44% 8% 23% 17% 7% 1	760
December	1st to 10th	Night	37% 7% 27% 22% 6%	789
	11th to 20th	Night	51% 8% 24% 15% 2	850
	21st to end	Night	48% 11% 26% 14% 1	935

Page generated at 2024-01-13 06:37:55. Version ac07

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