Twillingate
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Twillingate clear sky chart from 2005-11-06 to 2025-12-18.

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	20% 13% 5% 10% 6% 4 4 3 4 6% 24%	127591
	Night	21% 15% 5% 13% 7% 5% 4 3 4 5% 19%	123683
Transparency	Day	64% 3 11% 16% 6%	131017
	Night	68% 3 10% 13% 5%	128356
Seeing	Day	29% 10% 27% 23% 10% 2	19697
	Night	31% 11% 27% 22% 8% 1	26443

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	20% 22% 7% 17% 8% 4 3 2 3 3 10%	3176
	11th to 20th	Day	16% 21% 9% 20% 10% 4 3 2 2 3 9%	3476
	21st to end	Day	9% 13% 6% 19% 17% 10% 4 2 3 4 13%	3982
February	1st to 10th	Day	18% 13% 4 18% 14% 6% 5% 4 4 5% 10%	1600
	11th to 20th	Day	18% 19% 5% 11% 11% 5% 5% 4 4 3 15%	1784
	21st to end	Day	14% 13% 5% 13% 8% 9% 7% 4 4 5% 20%	1650
March	1st to 10th	Day	15% 12% 4 14% 15% 7% 5% 3 4 5% 16%	4474
	11th to 20th	Day	20% 15% 6% 12% 8% 6% 4 3 4 5% 16%	4875
	21st to end	Day	26% 15% 5% 11% 5% 3 3 3 4 4 20%	5649
April	1st to 10th	Day	19% 16% 5% 10% 5% 5% 4 4 5% 6% 21%	2404
	11th to 20th	Day	22% 14% 5% 7% 4 4 3 3 5% 6% 27%	2571
	21st to end	Day	20% 17% 5% 9% 4 4 3 3 4 5% 25%	2600
May	1st to 10th	Day	25% 16% 6% 9% 5% 4 4 3 4 4 19%	6106
	11th to 20th	Day	20% 14% 6% 11% 5% 4 4 3 4 5% 23%	6613
	21st to end	Day	25% 15% 4 8% 4 3 3 3 4 6% 26%	7428
June	1st to 10th	Day	29% 14% 4 7% 5% 4 4 3 4 5% 21%	3000
	11th to 20th	Day	25% 10% 3 7% 5% 4 4 3 5% 6% 26%	3000
	21st to end	Day	21% 11% 3 7% 5% 5% 5% 4 6% 6% 27%	3000
July	1st to 10th	Day	19% 11% 3 8% 5% 5% 4 3 5% 7% 31%	6800
	11th to 20th	Day	14% 7% 3 8% 5% 5% 5% 4 6% 8% 35%	6800
	21st to end	Day	20% 9% 2 7% 4 4 4 3 5% 8% 33%	6956
August	1st to 10th	Day	20% 10% 3 7% 4 4 4 3 6% 7% 31%	4564
	11th to 20th	Day	18% 8% 3 6% 3 3 4 3 4 5% 43%	4181
	21st to end	Day	19% 7% 2 6% 4 3 4 4 6% 8% 37%	4675
September	1st to 10th	Day	19% 8% 3 7% 4 3 4 3 4 8% 37%	2417
	11th to 20th	Day	26% 10% 2 7% 4 4 4 3 5% 7% 29%	2200
	21st to end	Day	20% 10% 3 7% 4 4 4 4 6% 7% 31%	2200
October	1st to 10th	Day	21% 12% 3 7% 4 5% 4 3 4 6% 31%	2140
	11th to 20th	Day	22% 17% 3 9% 4 3 4 3 4 6% 23%	1835
	21st to end	Day	27% 17% 3 7% 4 4 4 3 4 6% 20%	1980
November	1st to 10th	Day	25% 20% 5% 8% 4 4 4 2 4 5% 18%	1818
	11th to 20th	Day	23% 19% 7% 9% 5% 4 4 2 4 5% 19%	1632
	21st to end	Day	24% 19% 7% 12% 5% 3 3 3 3 4 16%	1470
December	1st to 10th	Day	16% 13% 6% 16% 6% 4 5% 3 4 5% 21%	2360
	11th to 20th	Day	19% 17% 7% 19% 7% 4 4 3 3 5% 12%	2677
	21st to end	Day	20% 16% 8% 26% 8% 4 3 2 3 2 9%	3498
January	1st to 10th	Night	20% 21% 8% 18% 9% 5% 4 2 3 3 7%	6789
	11th to 20th	Night	14% 20% 7% 21% 9% 6% 4 3 3 4 10%	6428
	21st to end	Night	8% 11% 5% 19% 14% 10% 6% 3 5% 5% 14%	6996
February	1st to 10th	Night	18% 14% 6% 20% 14% 6% 4 3 3 3 10%	2800
	11th to 20th	Night	20% 18% 5% 11% 10% 5% 4 3 4 4 14%	2499
	21st to end	Night	15% 12% 6% 13% 9% 6% 5% 3 5% 5% 20%	1980
March	1st to 10th	Night	17% 14% 4 17% 9% 5% 4 3 4 5% 18%	5366
	11th to 20th	Night	19% 15% 5% 14% 7% 6% 5% 4 5% 5% 16%	5084
	21st to end	Night	23% 15% 5% 11% 5% 5% 4 3 5% 5% 19%	5268
April	1st to 10th	Night	23% 18% 5% 11% 5% 4 3 3 4 5% 19%	1995
	11th to 20th	Night	24% 15% 6% 9% 3 3 3 3 4 5% 26%	1778
	21st to end	Night	25% 18% 5% 6% 4 3 4 2 4 5% 24%	1800
May	1st to 10th	Night	34% 17% 5% 7% 4 3 3 2 3 4 17%	3850
	11th to 20th	Night	24% 17% 8% 11% 4 4 3 2 3 4 21%	3299
	21st to end	Night	29% 14% 5% 7% 4 3 4 3 4 5% 23%	3468
June	1st to 10th	Night	32% 14% 5% 7% 4 3 5% 3 5% 5% 19%	1400
	11th to 20th	Night	28% 11% 4 8% 4 4 5% 3 5% 5% 24%	1400
	21st to end	Night	24% 14% 3 7% 4 3 5% 4 5% 6% 25%	1400
July	1st to 10th	Night	23% 13% 4 9% 5% 4 4 3 4 6% 26%	3179
	11th to 20th	Night	13% 10% 3 8% 6% 5% 5% 4 6% 7% 33%	3180
	21st to end	Night	22% 11% 3 8% 5% 4 4 3 4 6% 29%	3904
August	1st to 10th	Night	16% 8% 3 8% 6% 4 4 4 6% 8% 33%	2596
	11th to 20th	Night	17% 8% 3 7% 4 3 4 4 5% 6% 39%	2876
	21st to end	Night	21% 7% 2 6% 3 4 4 3 6% 8% 35%	3234
September	1st to 10th	Night	22% 8% 3 6% 3 3 4 3 5% 7% 35%	1980
	11th to 20th	Night	25% 12% 2 7% 4 4 4 3 4 5% 29%	2200
	21st to end	Night	21% 12% 4 7% 4 3 4 3 5% 6% 30%	2200
October	1st to 10th	Night	25% 12% 2 8% 4 4 4 3 4 6% 27%	2260
	11th to 20th	Night	25% 15% 3 7% 4 4 5% 3 5% 6% 23%	2560
	21st to end	Night	28% 19% 3 7% 3 3 3 3 4 5% 22%	2860
November	1st to 10th	Night	26% 20% 4 9% 6% 4 5% 3 4 4 16%	2700
	11th to 20th	Night	26% 20% 6% 9% 5% 4 4 3 4 6% 14%	2987
	21st to end	Night	24% 21% 8% 11% 5% 4 3 3 4 5% 13%	3150
December	1st to 10th	Night	15% 15% 6% 15% 7% 5% 4 3 4 5% 21%	5050
	11th to 20th	Night	23% 17% 8% 18% 7% 4 3 2 3 4 11%	5687
	21st to end	Night	18% 16% 9% 25% 7% 3 2 2 3 3 11%	7480

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	82% 2 5% 9% 1	3177
	11th to 20th	Day	82% 4 6% 5% 3	3505
	21st to end	Day	77% 3 5% 8% 5% 2	3982
February	1st to 10th	Day	77% 4 8% 6% 5% 1	1600
	11th to 20th	Day	75% 3 8% 9% 5%	1791
	21st to end	Day	67% 4 7% 13% 7%	1650
March	1st to 10th	Day	72% 4 6% 12% 6% 1	4478
	11th to 20th	Day	73% 3 8% 10% 5% 2	4875
	21st to end	Day	70% 2 7% 13% 7%	5649
April	1st to 10th	Day	65% 3 9% 15% 7% 1	2404
	11th to 20th	Day	60% 2 10% 19% 9% 1	2571
	21st to end	Day	65% 3 7% 15% 9% 1	2600
May	1st to 10th	Day	71% 2 10% 13% 4 1	6118
	11th to 20th	Day	66% 2 10% 16% 6%	6617
	21st to end	Day	62% 2 12% 19% 5%	7428
June	1st to 10th	Day	66% 3 10% 16% 4	3000
	11th to 20th	Day	59% 4 12% 20% 5% 1	3000
	21st to end	Day	57% 5% 12% 18% 7% 1	3000
July	1st to 10th	Day	54% 3 14% 22% 7%	6725
	11th to 20th	Day	50% 3 16% 25% 6%	6718
	21st to end	Day	51% 3 18% 24% 4	6758
August	1st to 10th	Day	53% 5% 17% 21% 4	4550
	11th to 20th	Day	45% 3 16% 24% 11% 2	4220
	21st to end	Day	47% 3 17% 25% 7%	4675
September	1st to 10th	Day	48% 4 13% 25% 8% 1	2417
	11th to 20th	Day	57% 4 15% 18% 6%	2200
	21st to end	Day	52% 4 18% 19% 6%	2200
October	1st to 10th	Day	62% 3 11% 19% 6%	3494
	11th to 20th	Day	67% 3 10% 16% 4	2970
	21st to end	Day	65% 3 10% 14% 8% 1	3191
November	1st to 10th	Day	70% 4 10% 10% 4	1818
	11th to 20th	Day	69% 4 10% 11% 5% 1	1632
	21st to end	Day	72% 5% 9% 9% 5%	1470
December	1st to 10th	Day	66% 3 9% 14% 8%	2360
	11th to 20th	Day	78% 3 14% 4 2	2676
	21st to end	Day	85% 2 6% 6% 1	3498
January	1st to 10th	Night	84% 2 6% 5% 2	6789
	11th to 20th	Night	78% 5% 5% 8% 4	6474
	21st to end	Night	72% 3 11% 7% 6% 1	6996
February	1st to 10th	Night	80% 3 6% 7% 4	2800
	11th to 20th	Night	75% 3 8% 10% 3	2503
	21st to end	Night	65% 5% 7% 16% 7% 1	1980
March	1st to 10th	Night	69% 3 9% 12% 5% 2	5375
	11th to 20th	Night	71% 3 9% 10% 6% 1	5085
	21st to end	Night	69% 2 9% 14% 6%	5268
April	1st to 10th	Night	69% 3 5% 13% 9%	1995
	11th to 20th	Night	62% 2 9% 19% 7% 1	1778
	21st to end	Night	64% 3 7% 15% 9% 1	1800
May	1st to 10th	Night	73% 2 9% 13% 3	3855
	11th to 20th	Night	71% 1 7% 15% 5%	3300
	21st to end	Night	67% 2 9% 17% 4	3469
June	1st to 10th	Night	68% 4 10% 12% 6%	1400
	11th to 20th	Night	62% 3 12% 17% 5%	1400
	21st to end	Night	61% 4 11% 17% 6% 1	1400
July	1st to 10th	Night	60% 3 13% 21% 3	3146
	11th to 20th	Night	52% 3 12% 23% 9%	3138
	21st to end	Night	58% 2 15% 22% 3	3788
August	1st to 10th	Night	49% 5% 16% 25% 5%	2585
	11th to 20th	Night	47% 4 15% 22% 11% 1	2903
	21st to end	Night	49% 2 15% 27% 6%	3233
September	1st to 10th	Night	50% 4 13% 24% 9% 1	1980
	11th to 20th	Night	58% 4 12% 17% 8%	2200
	21st to end	Night	56% 4 14% 19% 7%	2200
October	1st to 10th	Night	63% 3 13% 15% 5%	3689
	11th to 20th	Night	65% 3 14% 13% 5%	4161
	21st to end	Night	64% 2 13% 13% 6% 1	4610
November	1st to 10th	Night	72% 4 8% 11% 5%	2700
	11th to 20th	Night	72% 5% 9% 12% 2	2987
	21st to end	Night	75% 5% 8% 8% 4	3150
December	1st to 10th	Night	67% 3 6% 15% 9%	5050
	11th to 20th	Night	80% 3 10% 4 3	5689
	21st to end	Night	81% 3 6% 9% 2	7480

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	29% 14% 34% 18% 4 1	400
	11th to 20th	Day	27% 17% 35% 18% 4	400
	21st to end	Day	29% 21% 31% 17% 2	440
February	1st to 10th	Day	26% 21% 34% 15% 5%	400
	11th to 20th	Day	27% 22% 33% 15% 3 1	396
	21st to end	Day	19% 18% 38% 17% 5% 2	331
March	1st to 10th	Day	26% 13% 38% 18% 6% 1	400
	11th to 20th	Day	28% 16% 24% 20% 11% 2	400
	21st to end	Day	34% 12% 27% 19% 6% 2	480
April	1st to 10th	Day	29% 13% 33% 19% 5% 1	504
	11th to 20th	Day	31% 8% 27% 24% 7% 2	689
	21st to end	Day	32% 8% 27% 24% 8% 1	700
May	1st to 10th	Day	35% 7% 23% 21% 11% 3	703
	11th to 20th	Day	28% 5% 27% 24% 13% 3	724
	21st to end	Day	34% 6% 23% 26% 9% 1	790
June	1st to 10th	Day	37% 7% 21% 22% 9% 3	730
	11th to 20th	Day	30% 6% 22% 26% 14% 2	730
	21st to end	Day	26% 3 24% 28% 14% 3	730
July	1st to 10th	Day	27% 4 23% 32% 11% 3	720
	11th to 20th	Day	23% 3 23% 29% 20% 2	718
	21st to end	Day	25% 4 24% 32% 14% 1	795
August	1st to 10th	Day	25% 6% 19% 30% 15% 4	725
	11th to 20th	Day	24% 3 21% 29% 20% 3	717
	21st to end	Day	27% 5% 23% 25% 17% 4	803
September	1st to 10th	Day	25% 8% 26% 26% 11% 3	554
	11th to 20th	Day	35% 9% 23% 24% 7% 1	420
	21st to end	Day	26% 11% 34% 20% 7% 1	420
October	1st to 10th	Day	27% 11% 35% 19% 7% 1	420
	11th to 20th	Day	37% 10% 25% 16% 10% 2	420
	21st to end	Day	33% 15% 26% 19% 6% 2	462
November	1st to 10th	Day	40% 15% 30% 12% 2	425
	11th to 20th	Day	37% 17% 24% 16% 5% 1	430
	21st to end	Day	36% 17% 32% 13% 2	430
December	1st to 10th	Day	29% 16% 32% 17% 6%	430
	11th to 20th	Day	31% 25% 27% 15% 2	421
	21st to end	Day	27% 18% 30% 18% 7% 1	440
January	1st to 10th	Night	30% 18% 29% 18% 5% 1	900
	11th to 20th	Night	27% 17% 36% 14% 6%	900
	21st to end	Night	25% 19% 36% 16% 4	990
February	1st to 10th	Night	27% 21% 31% 17% 3 1	900
	11th to 20th	Night	32% 17% 33% 15% 3 1	861
	21st to end	Night	23% 12% 37% 19% 7% 2	660
March	1st to 10th	Night	27% 16% 32% 19% 5% 1	800
	11th to 20th	Night	25% 10% 30% 24% 10% 1	653
	21st to end	Night	34% 13% 26% 21% 6% 1	660
April	1st to 10th	Night	32% 12% 30% 19% 6% 1	600
	11th to 20th	Night	32% 8% 29% 20% 9% 1	594
	21st to end	Night	35% 5% 26% 28% 6% 1	600
May	1st to 10th	Night	38% 5% 19% 26% 11% 2	600
	11th to 20th	Night	38% 5% 19% 23% 12% 2	592
	21st to end	Night	36% 5% 24% 26% 8% 1	649
June	1st to 10th	Night	38% 6% 18% 28% 10% 1	600
	11th to 20th	Night	35% 4 19% 27% 14% 2	600
	21st to end	Night	32% 6% 21% 26% 14% 1	600
July	1st to 10th	Night	28% 3 23% 34% 11% 2	586
	11th to 20th	Night	24% 3 26% 35% 12% 1	582
	21st to end	Night	26% 5% 23% 32% 13% 1	656
August	1st to 10th	Night	25% 4 19% 35% 16% 2	598
	11th to 20th	Night	24% 3 22% 33% 17% 1	592
	21st to end	Night	27% 5% 20% 30% 16% 2	660
September	1st to 10th	Night	26% 6% 27% 31% 10% 1	600
	11th to 20th	Night	33% 9% 24% 29% 6%	600
	21st to end	Night	32% 7% 31% 23% 6% 1	600
October	1st to 10th	Night	35% 8% 28% 22% 6% 1	633
	11th to 20th	Night	36% 9% 23% 22% 9% 1	870
	21st to end	Night	38% 13% 21% 21% 7% 1	1001
November	1st to 10th	Night	37% 15% 28% 16% 3	930
	11th to 20th	Night	38% 12% 27% 16% 5% 1	950
	21st to end	Night	36% 16% 30% 15% 3	950
December	1st to 10th	Night	31% 16% 30% 18% 5% 1	950
	11th to 20th	Night	35% 17% 30% 14% 4	936
	21st to end	Night	26% 18% 29% 19% 7% 1	990

Page generated at 2025-12-15 02:13:50. Version ac07

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