Happy Valley-Goose Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Happy Valley-Goose Bay clear sky chart from 2005-11-06 to 2024-01-13.

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	20% 12% 5% 8% 6% 3 5% 5% 5% 6% 26%	74520
	Night	18% 13% 5% 8% 7% 3 5% 4 5% 5% 27%	75221
Transparency	Day	60% 8% 12% 15% 6%	74196
	Night	59% 7% 12% 16% 6%	75080
Seeing	Day	27% 13% 27% 21% 10% 2	15829
	Night	25% 12% 28% 25% 9% 1	22950

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% 15% 5% 9% 6% 5% 6% 6% 4 5% 29%	1151
	11th to 20th	Day	12% 17% 6% 7% 5% 4 4 6% 5% 6% 27%	1280
	21st to end	Day	11% 13% 5% 8% 7% 4 4 6% 5% 6% 31%	1488
February	1st to 10th	Day	11% 11% 4 8% 6% 5% 5% 5% 5% 7% 34%	1440
	11th to 20th	Day	10% 14% 7% 8% 7% 2 6% 5% 6% 7% 28%	1561
	21st to end	Day	8% 13% 5% 10% 7% 4 5% 5% 6% 7% 29%	1381
March	1st to 10th	Day	12% 16% 8% 8% 7% 3 5% 4 5% 5% 27%	1796
	11th to 20th	Day	12% 19% 7% 8% 8% 4 4 5% 5% 5% 23%	1913
	21st to end	Day	16% 18% 6% 9% 6% 4 4 4 4 5% 26%	2328
April	1st to 10th	Day	22% 19% 7% 9% 6% 3 4 3 4 4 20%	2160
	11th to 20th	Day	15% 16% 5% 9% 7% 3 5% 5% 4 6% 26%	2258
	21st to end	Day	20% 14% 7% 9% 6% 3 5% 3 4 4 25%	2520
May	1st to 10th	Day	24% 16% 5% 7% 5% 3 4 4 5% 5% 20%	2520
	11th to 20th	Day	25% 13% 4 7% 6% 3 4 4 5% 6% 23%	2499
	21st to end	Day	27% 13% 5% 7% 6% 3 5% 4 4 5% 22%	3094
June	1st to 10th	Day	28% 11% 4 8% 6% 3 4 4 4 5% 22%	2880
	11th to 20th	Day	29% 9% 3 7% 6% 3 5% 4 5% 6% 24%	2880
	21st to end	Day	24% 9% 4 6% 7% 4 5% 4 5% 7% 25%	2880
July	1st to 10th	Day	25% 9% 4 7% 6% 3 5% 5% 6% 7% 23%	2880
	11th to 20th	Day	21% 8% 4 6% 7% 3 6% 6% 6% 6% 27%	2816
	21st to end	Day	22% 8% 4 8% 8% 4 6% 6% 6% 7% 21%	2861
August	1st to 10th	Day	21% 8% 3 8% 6% 3 6% 5% 7% 7% 27%	2506
	11th to 20th	Day	24% 8% 3 5% 6% 4 5% 5% 5% 8% 28%	2482
	21st to end	Day	24% 7% 3 6% 6% 3 5% 6% 5% 7% 29%	2527
September	1st to 10th	Day	20% 8% 3 7% 6% 4 5% 4 5% 7% 32%	2160
	11th to 20th	Day	21% 10% 3 5% 6% 4 4 5% 5% 7% 30%	2156
	21st to end	Day	21% 9% 4 9% 7% 3 5% 4 6% 6% 25%	1919
October	1st to 10th	Day	21% 13% 4 7% 6% 3 4 5% 5% 5% 27%	1800
	11th to 20th	Day	27% 11% 3 7% 7% 4 5% 5% 4 5% 22%	1709
	21st to end	Day	22% 14% 4 6% 6% 3 4 4 5% 5% 25%	1751
November	1st to 10th	Day	21% 16% 5% 8% 6% 2 4 3 4 6% 25%	1485
	11th to 20th	Day	16% 16% 4 7% 5% 4 5% 5% 4 5% 29%	1419
	21st to end	Day	20% 17% 4 8% 5% 3 4 4 5% 5% 25%	1330
December	1st to 10th	Day	12% 15% 6% 8% 7% 4 5% 4 3 5% 31%	1170
	11th to 20th	Day	17% 14% 7% 8% 7% 3 4 4 4 6% 28%	1430
	21st to end	Day	12% 14% 6% 12% 9% 4 4 4 5% 5% 24%	2090
January	1st to 10th	Night	15% 15% 5% 9% 7% 3 4 3 3 6% 28%	3012
	11th to 20th	Night	13% 15% 5% 10% 6% 3 5% 5% 4 6% 28%	2742
	21st to end	Night	10% 14% 6% 9% 8% 3 6% 5% 5% 5% 29%	2866
February	1st to 10th	Night	9% 9% 5% 9% 7% 4 5% 4 7% 7% 35%	2520
	11th to 20th	Night	11% 17% 5% 9% 7% 4 5% 5% 5% 5% 27%	2282
	21st to end	Night	8% 16% 6% 9% 7% 3 5% 4 5% 6% 30%	1874
March	1st to 10th	Night	12% 18% 8% 8% 7% 3 4 5% 4 4 25%	2151
	11th to 20th	Night	13% 19% 7% 10% 7% 3 5% 4 4 4 24%	2043
	21st to end	Night	17% 21% 6% 8% 6% 3 4 4 4 4 23%	2027
April	1st to 10th	Night	24% 19% 6% 9% 6% 3 3 3 3 3 20%	1800
	11th to 20th	Night	20% 13% 5% 7% 6% 3 5% 5% 4 5% 27%	1650
	21st to end	Night	22% 14% 5% 6% 6% 3 5% 3 3 6% 26%	1440
May	1st to 10th	Night	24% 13% 5% 6% 6% 3 4 2 5% 5% 28%	1440
	11th to 20th	Night	25% 14% 4 5% 4 3 4 4 4 5% 28%	1392
	21st to end	Night	30% 12% 3 6% 5% 3 3 4 5% 5% 24%	1196
June	1st to 10th	Night	28% 11% 4 7% 6% 3 5% 4 4 4 25%	1080
	11th to 20th	Night	25% 7% 3 6% 6% 5% 5% 6% 6% 6% 24%	1080
	21st to end	Night	25% 7% 4 5% 7% 4 4 4 5% 6% 29%	1080
July	1st to 10th	Night	19% 9% 3 8% 7% 4 6% 5% 7% 7% 26%	1080
	11th to 20th	Night	18% 9% 3 9% 7% 5% 6% 5% 5% 6% 28%	1142
	21st to end	Night	20% 9% 3 7% 6% 5% 7% 7% 7% 7% 22%	1439
August	1st to 10th	Night	19% 8% 3 9% 7% 4 4 5% 6% 5% 29%	1433
	11th to 20th	Night	20% 8% 3 7% 6% 3 5% 6% 6% 7% 29%	1418
	21st to end	Night	23% 7% 3 7% 5% 4 6% 5% 6% 7% 28%	1825
September	1st to 10th	Night	22% 8% 3 5% 7% 3 4 4 6% 6% 31%	1800
	11th to 20th	Night	26% 8% 2 6% 5% 3 4 5% 4 6% 30%	1804
	21st to end	Night	26% 8% 3 6% 6% 3 4 4 5% 5% 29%	2038
October	1st to 10th	Night	23% 11% 4 7% 6% 4 5% 6% 5% 5% 26%	2160
	11th to 20th	Night	26% 12% 3 7% 6% 3 4 4 5% 6% 24%	2250
	21st to end	Night	26% 10% 4 7% 5% 3 4 4 3 5% 27%	2602
November	1st to 10th	Night	19% 14% 5% 8% 7% 4 5% 4 4 5% 23%	2593
	11th to 20th	Night	17% 15% 5% 8% 6% 3 4 4 5% 5% 29%	2760
	21st to end	Night	20% 18% 5% 7% 6% 3 3 4 4 5% 25%	2850
December	1st to 10th	Night	14% 16% 7% 8% 7% 4 5% 4 4 5% 25%	3006
	11th to 20th	Night	19% 15% 5% 9% 7% 3 4 4 4 5% 25%	3769
	21st to end	Night	12% 14% 5% 10% 12% 4 5% 4 4 5% 23%	5577

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	58% 6% 9% 19% 7% 1	1152
	11th to 20th	Day	58% 5% 11% 15% 10%	1280
	21st to end	Day	53% 6% 10% 19% 12% 1	1488
February	1st to 10th	Day	50% 5% 13% 21% 10% 1	1440
	11th to 20th	Day	54% 6% 13% 18% 8%	1569
	21st to end	Day	54% 6% 9% 20% 10% 1	1381
March	1st to 10th	Day	60% 6% 11% 16% 6% 1	1800
	11th to 20th	Day	64% 5% 8% 14% 8%	1913
	21st to end	Day	63% 5% 8% 14% 9% 1	2328
April	1st to 10th	Day	70% 5% 7% 10% 6% 2	2160
	11th to 20th	Day	60% 7% 11% 16% 7%	2258
	21st to end	Day	64% 6% 10% 15% 5%	2520
May	1st to 10th	Day	65% 7% 10% 13% 4 1	2520
	11th to 20th	Day	62% 8% 12% 12% 6%	2503
	21st to end	Day	65% 6% 10% 15% 4	3094
June	1st to 10th	Day	65% 7% 10% 14% 4	2880
	11th to 20th	Day	63% 7% 11% 15% 4	2880
	21st to end	Day	59% 9% 12% 15% 5%	2880
July	1st to 10th	Day	59% 10% 14% 13% 4	2800
	11th to 20th	Day	55% 11% 13% 17% 4	2729
	21st to end	Day	59% 11% 13% 14% 3	2701
August	1st to 10th	Day	54% 11% 16% 15% 4	2492
	11th to 20th	Day	55% 9% 15% 17% 3	2482
	21st to end	Day	54% 9% 16% 16% 5%	2527
September	1st to 10th	Day	53% 7% 15% 20% 4	2160
	11th to 20th	Day	54% 9% 14% 18% 5%	2156
	21st to end	Day	59% 9% 12% 15% 5%	1919
October	1st to 10th	Day	59% 7% 13% 15% 6% 1	1800
	11th to 20th	Day	66% 7% 10% 13% 4	1709
	21st to end	Day	61% 9% 13% 10% 6% 1	1751
November	1st to 10th	Day	62% 7% 12% 13% 5%	1485
	11th to 20th	Day	57% 8% 14% 19% 3	1419
	21st to end	Day	64% 7% 10% 16% 4	1330
December	1st to 10th	Day	58% 8% 12% 17% 6%	1170
	11th to 20th	Day	59% 7% 12% 15% 6% 1	1430
	21st to end	Day	58% 9% 11% 15% 6% 1	2090
January	1st to 10th	Night	58% 5% 10% 19% 8% 1	3012
	11th to 20th	Night	57% 6% 13% 17% 8%	2742
	21st to end	Night	56% 6% 10% 19% 10% 1	2866
February	1st to 10th	Night	48% 5% 13% 24% 9% 1	2520
	11th to 20th	Night	59% 5% 11% 16% 9%	2285
	21st to end	Night	54% 5% 9% 21% 10% 1	1874
March	1st to 10th	Night	61% 5% 10% 14% 9% 1	2160
	11th to 20th	Night	65% 4 8% 14% 8% 1	2044
	21st to end	Night	66% 5% 8% 12% 8% 1	2027
April	1st to 10th	Night	71% 4 5% 12% 7% 1	1800
	11th to 20th	Night	58% 6% 10% 16% 10%	1650
	21st to end	Night	60% 8% 9% 16% 7% 1	1440
May	1st to 10th	Night	61% 5% 12% 16% 6% 1	1440
	11th to 20th	Night	59% 6% 12% 15% 7%	1393
	21st to end	Night	63% 5% 10% 16% 6%	1197
June	1st to 10th	Night	62% 6% 11% 14% 6% 1	1080
	11th to 20th	Night	58% 9% 12% 17% 4	1080
	21st to end	Night	56% 7% 15% 14% 8%	1080
July	1st to 10th	Night	53% 12% 16% 16% 3	1050
	11th to 20th	Night	54% 8% 14% 18% 5%	1106
	21st to end	Night	56% 12% 14% 15% 3	1359
August	1st to 10th	Night	53% 11% 16% 16% 3	1422
	11th to 20th	Night	53% 8% 16% 19% 4	1418
	21st to end	Night	54% 10% 16% 15% 5%	1825
September	1st to 10th	Night	52% 7% 15% 20% 6%	1800
	11th to 20th	Night	54% 8% 15% 17% 5%	1804
	21st to end	Night	58% 7% 13% 17% 6%	2038
October	1st to 10th	Night	59% 9% 11% 15% 6% 1	2160
	11th to 20th	Night	61% 8% 11% 14% 5%	2250
	21st to end	Night	59% 8% 12% 16% 4	2602
November	1st to 10th	Night	64% 8% 12% 12% 4	2593
	11th to 20th	Night	57% 7% 14% 17% 4	2760
	21st to end	Night	62% 7% 11% 16% 3	2850
December	1st to 10th	Night	61% 8% 12% 13% 5%	3006
	11th to 20th	Night	62% 7% 12% 15% 4	3770
	21st to end	Night	60% 8% 10% 16% 6% 1	5577

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	11% 12% 38% 26% 11% 2	180
	11th to 20th	Day	23% 13% 32% 20% 11% 1	166
	21st to end	Day	17% 14% 31% 30% 8%	278
February	1st to 10th	Day	17% 13% 29% 29% 9% 3	340
	11th to 20th	Day	15% 14% 33% 24% 12% 1	336
	21st to end	Day	13% 17% 35% 21% 10% 5%	280
March	1st to 10th	Day	17% 15% 29% 25% 12% 3	340
	11th to 20th	Day	21% 13% 27% 24% 13% 3	391
	21st to end	Day	23% 17% 32% 20% 6% 2	462
April	1st to 10th	Day	30% 16% 28% 16% 8% 2	420
	11th to 20th	Day	21% 13% 33% 19% 9% 5%	462
	21st to end	Day	29% 15% 23% 18% 12% 3	600
May	1st to 10th	Day	34% 13% 23% 19% 10% 2	603
	11th to 20th	Day	36% 12% 20% 16% 13% 3	624
	21st to end	Day	32% 13% 27% 19% 7% 2	680
June	1st to 10th	Day	34% 11% 24% 20% 8% 2	630
	11th to 20th	Day	37% 10% 20% 22% 10% 2	630
	21st to end	Day	31% 13% 24% 19% 10% 3	630
July	1st to 10th	Day	29% 8% 21% 24% 16% 3	620
	11th to 20th	Day	24% 11% 26% 31% 8% 1	618
	21st to end	Day	26% 6% 22% 27% 16% 3	685
August	1st to 10th	Day	27% 7% 23% 23% 17% 3	625
	11th to 20th	Day	27% 8% 25% 23% 15% 2	617
	21st to end	Day	29% 9% 26% 22% 12% 3	545
September	1st to 10th	Day	26% 15% 32% 18% 8% 1	450
	11th to 20th	Day	28% 18% 29% 15% 8% 2	448
	21st to end	Day	26% 20% 33% 16% 5% 1	360
October	1st to 10th	Day	26% 25% 29% 14% 5% 1	360
	11th to 20th	Day	34% 15% 24% 18% 7% 3	360
	21st to end	Day	28% 17% 26% 17% 9% 3	396
November	1st to 10th	Day	28% 21% 28% 18% 4 1	365
	11th to 20th	Day	26% 15% 32% 21% 6% 1	370
	21st to end	Day	34% 12% 28% 22% 4 1	370
December	1st to 10th	Day	23% 12% 33% 20% 10% 2	210
	11th to 20th	Day	23% 19% 34% 20% 3 1	180
	21st to end	Day	21% 19% 28% 20% 10% 2	198
January	1st to 10th	Night	24% 9% 32% 26% 9% 1	850
	11th to 20th	Night	20% 12% 34% 26% 7%	814
	21st to end	Night	17% 11% 32% 31% 9%	880
February	1st to 10th	Night	15% 9% 32% 30% 11% 2	800
	11th to 20th	Night	21% 12% 31% 26% 8% 2	707
	21st to end	Night	17% 10% 31% 25% 13% 3	592
March	1st to 10th	Night	18% 14% 28% 25% 12% 3	720
	11th to 20th	Night	21% 13% 27% 28% 10% 1	720
	21st to end	Night	28% 12% 29% 23% 7% 1	641
April	1st to 10th	Night	32% 13% 23% 25% 6%	540
	11th to 20th	Night	24% 12% 28% 24% 10% 2	534
	21st to end	Night	28% 11% 24% 26% 10% 1	540
May	1st to 10th	Night	29% 8% 23% 30% 9% 1	540
	11th to 20th	Night	33% 11% 22% 21% 12% 1	532
	21st to end	Night	35% 11% 22% 22% 10% 1	423
June	1st to 10th	Night	33% 8% 21% 29% 9%	360
	11th to 20th	Night	27% 8% 27% 30% 7%	360
	21st to end	Night	24% 8% 25% 27% 17%	360
July	1st to 10th	Night	24% 6% 21% 31% 17% 1	350
	11th to 20th	Night	18% 9% 29% 34% 9%	348
	21st to end	Night	23% 6% 19% 38% 14%	456
August	1st to 10th	Night	22% 7% 25% 29% 16% 1	538
	11th to 20th	Night	24% 8% 23% 33% 13% 1	532
	21st to end	Night	23% 9% 26% 29% 13% 1	594
September	1st to 10th	Night	28% 12% 26% 28% 6%	540
	11th to 20th	Night	31% 11% 29% 24% 5%	540
	21st to end	Night	30% 12% 32% 21% 5%	598
October	1st to 10th	Night	29% 16% 29% 21% 5%	720
	11th to 20th	Night	31% 12% 26% 23% 8%	765
	21st to end	Night	32% 13% 25% 21% 9% 1	891
November	1st to 10th	Night	28% 16% 30% 20% 5% 1	830
	11th to 20th	Night	26% 14% 32% 23% 4 1	850
	21st to end	Night	32% 12% 33% 18% 5%	850
December	1st to 10th	Night	23% 15% 30% 21% 10% 1	850
	11th to 20th	Night	23% 15% 31% 22% 7% 1	850
	21st to end	Night	22% 13% 30% 22% 12% 1	935

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