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 2024-11-11.

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	21% 13% 5% 10% 6% 4 4 3 5% 6% 24%	101908
	Night	22% 15% 5% 12% 6% 4 4 3 4 5% 19%	97394
Transparency	Day	63% 3 11% 16% 6%	105352
	Night	68% 4 10% 13% 5%	102050
Seeing	Day	29% 10% 26% 23% 10% 2	18181
	Night	31% 11% 27% 22% 8% 1	24881

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	14% 20% 7% 21% 11% 4 4 2 3 4 10%	2216
	11th to 20th	Day	19% 17% 8% 22% 11% 4 4 2 3 3 8%	2441
	21st to end	Day	11% 15% 6% 17% 11% 11% 4 3 3 4 14%	2783
February	1st to 10th	Day	18% 14% 4 18% 13% 6% 5% 4 4 5% 10%	1520
	11th to 20th	Day	18% 20% 5% 11% 10% 5% 6% 4 4 3 15%	1692
	21st to end	Day	13% 13% 5% 12% 8% 9% 7% 4 4 5% 20%	1570
March	1st to 10th	Day	15% 13% 4 14% 11% 6% 5% 3 5% 5% 20%	3114
	11th to 20th	Day	21% 17% 6% 12% 7% 5% 4 3 5% 5% 14%	3403
	21st to end	Day	28% 14% 5% 9% 5% 3 3 3 4 5% 22%	3943
April	1st to 10th	Day	19% 16% 5% 10% 5% 5% 4 4 5% 6% 21%	2284
	11th to 20th	Day	22% 14% 5% 7% 4 4 3 3 5% 6% 27%	2441
	21st to end	Day	20% 18% 5% 9% 4 4 3 3 4 5% 25%	2470
May	1st to 10th	Day	26% 17% 7% 9% 5% 4 4 3 4 4 17%	4256
	11th to 20th	Day	22% 14% 7% 11% 5% 4 4 3 5% 6% 19%	4602
	21st to end	Day	26% 14% 5% 8% 5% 3 4 3 4 5% 23%	5173
June	1st to 10th	Day	29% 15% 4 7% 5% 5% 4 3 4 5% 20%	2850
	11th to 20th	Day	26% 11% 3 7% 5% 4 4 3 5% 6% 25%	2850
	21st to end	Day	22% 11% 3 8% 5% 5% 5% 4 5% 6% 27%	2850
July	1st to 10th	Day	19% 12% 3 8% 5% 5% 5% 3 5% 6% 29%	4750
	11th to 20th	Day	16% 8% 3 8% 5% 5% 5% 4 6% 7% 34%	4750
	21st to end	Day	14% 7% 2 6% 4 4 4 4 6% 9% 39%	4831
August	1st to 10th	Day	20% 10% 3 7% 4 4 4 3 6% 7% 29%	4424
	11th to 20th	Day	18% 8% 3 6% 3 3 4 3 4 5% 43%	4051
	21st to end	Day	19% 7% 2 6% 4 3 4 4 6% 8% 37%	4532
September	1st to 10th	Day	20% 8% 3 7% 4 3 4 3 4 7% 36%	2297
	11th to 20th	Day	27% 9% 2 7% 4 4 4 3 5% 6% 30%	2090
	21st to end	Day	21% 10% 3 7% 4 4 4 4 6% 7% 31%	2090
October	1st to 10th	Day	22% 12% 3 8% 4 4 3 3 4 5% 31%	2033
	11th to 20th	Day	22% 17% 3 9% 4 4 4 3 4 7% 23%	1743
	21st to end	Day	28% 17% 3 7% 4 4 4 3 4 6% 20%	1881
November	1st to 10th	Day	24% 20% 5% 8% 4 4 4 3 4 5% 18%	1730
	11th to 20th	Day	21% 19% 7% 9% 5% 4 4 2 4 5% 19%	1478
	21st to end	Day	23% 18% 8% 12% 5% 3 3 3 4 4 17%	1330
December	1st to 10th	Day	22% 20% 8% 14% 5% 3 4 3 4 5% 12%	1330
	11th to 20th	Day	25% 19% 7% 17% 7% 3 3 2 3 4 9%	1668
	21st to end	Day	25% 18% 7% 23% 8% 4 3 2 3 2 6%	2442
January	1st to 10th	Night	14% 19% 8% 21% 12% 5% 4 3 4 3 7%	4739
	11th to 20th	Night	13% 16% 6% 22% 10% 6% 4 3 3 4 12%	4528
	21st to end	Night	11% 14% 6% 19% 13% 7% 6% 2 4 4 14%	4884
February	1st to 10th	Night	18% 14% 6% 20% 13% 6% 4 3 3 3 10%	2660
	11th to 20th	Night	21% 18% 5% 11% 9% 5% 4 4 4 4 15%	2372
	21st to end	Night	15% 12% 6% 12% 9% 6% 5% 4 5% 5% 21%	1884
March	1st to 10th	Night	18% 15% 4 15% 7% 5% 4 3 5% 5% 18%	3726
	11th to 20th	Night	20% 17% 5% 13% 8% 6% 5% 4 5% 4 13%	3556
	21st to end	Night	26% 15% 5% 11% 5% 4 4 3 4 5% 20%	3674
April	1st to 10th	Night	23% 18% 5% 11% 5% 4 3 3 4 5% 19%	1895
	11th to 20th	Night	24% 16% 6% 9% 3 3 2 3 4 5% 26%	1688
	21st to end	Night	25% 17% 5% 6% 4 3 4 2 4 5% 24%	1710
May	1st to 10th	Night	33% 18% 6% 8% 4 3 3 2 4 5% 15%	2690
	11th to 20th	Night	25% 17% 9% 13% 4 4 3 2 3 4 16%	2300
	21st to end	Night	31% 14% 6% 7% 4 3 4 3 4 5% 20%	2412
June	1st to 10th	Night	32% 14% 5% 7% 4 3 5% 3 5% 5% 17%	1330
	11th to 20th	Night	29% 11% 4 8% 4 4 4 3 5% 5% 23%	1330
	21st to end	Night	25% 14% 3 7% 4 3 4 4 4 6% 26%	1330
July	1st to 10th	Night	23% 13% 4 9% 5% 5% 4 3 4 7% 26%	2220
	11th to 20th	Night	14% 12% 4 9% 6% 5% 5% 5% 6% 6% 28%	2220
	21st to end	Night	18% 9% 3 7% 5% 4 4 3 4 7% 37%	2719
August	1st to 10th	Night	16% 8% 3 8% 6% 4 4 4 6% 8% 32%	2516
	11th to 20th	Night	17% 8% 3 7% 4 3 5% 4 5% 6% 39%	2786
	21st to end	Night	21% 7% 2 6% 4 4 4 3 6% 8% 36%	3135
September	1st to 10th	Night	22% 9% 3 6% 3 3 4 3 5% 7% 34%	1881
	11th to 20th	Night	25% 12% 2 7% 4 4 4 3 4 5% 30%	2090
	21st to end	Night	22% 12% 4 8% 4 3 4 3 5% 6% 30%	2090
October	1st to 10th	Night	26% 12% 2 8% 4 4 4 3 4 6% 27%	2147
	11th to 20th	Night	24% 15% 3 7% 4 4 5% 3 5% 6% 22%	2432
	21st to end	Night	30% 19% 3 7% 3 3 3 3 4 5% 21%	2717
November	1st to 10th	Night	25% 20% 4 9% 6% 4 5% 3 4 5% 16%	2568
	11th to 20th	Night	24% 20% 7% 9% 5% 4 4 3 4 6% 15%	2709
	21st to end	Night	23% 20% 8% 12% 5% 4 3 3 4 5% 14%	2850
December	1st to 10th	Night	20% 21% 8% 15% 7% 5% 4 3 4 4 11%	2850
	11th to 20th	Night	28% 22% 7% 19% 8% 3 2 1 2 2 5%	3531
	21st to end	Night	23% 18% 9% 21% 6% 3 2 2 3 3 10%	5225

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	81% 3 7% 6% 1	2217
	11th to 20th	Day	81% 6% 5% 5% 4	2441
	21st to end	Day	75% 4 4 10% 5% 1	2783
February	1st to 10th	Day	76% 4 8% 6% 5% 1	1520
	11th to 20th	Day	75% 3 8% 9% 5%	1699
	21st to end	Day	67% 4 8% 13% 8% 1	1570
March	1st to 10th	Day	66% 4 9% 14% 6% 1	3118
	11th to 20th	Day	73% 3 8% 10% 5%	3403
	21st to end	Day	67% 3 10% 14% 6%	3943
April	1st to 10th	Day	65% 3 9% 15% 7% 1	2284
	11th to 20th	Day	60% 2 10% 18% 8% 1	2441
	21st to end	Day	64% 3 7% 16% 9% 1	2470
May	1st to 10th	Day	73% 2 9% 12% 3	4271
	11th to 20th	Day	68% 3 11% 14% 5%	4606
	21st to end	Day	66% 3 8% 17% 6%	5173
June	1st to 10th	Day	68% 4 10% 15% 4	2850
	11th to 20th	Day	59% 4 12% 19% 5% 1	2850
	21st to end	Day	57% 5% 13% 17% 7% 1	2850
July	1st to 10th	Day	57% 3 14% 20% 6%	4675
	11th to 20th	Day	51% 3 18% 23% 5%	4668
	21st to end	Day	42% 4 20% 29% 5%	4677
August	1st to 10th	Day	55% 5% 17% 21% 3	4410
	11th to 20th	Day	45% 3 16% 24% 11% 2	4090
	21st to end	Day	47% 3 17% 25% 7%	4532
September	1st to 10th	Day	49% 4 12% 25% 8% 1	2297
	11th to 20th	Day	56% 4 15% 18% 6%	2090
	21st to end	Day	53% 4 19% 18% 6%	2090
October	1st to 10th	Day	62% 3 11% 18% 6%	3387
	11th to 20th	Day	67% 3 9% 16% 5%	2878
	21st to end	Day	65% 3 10% 13% 8% 1	3092
November	1st to 10th	Day	70% 5% 11% 10% 4	1730
	11th to 20th	Day	68% 4 11% 10% 5% 1	1478
	21st to end	Day	72% 5% 9% 9% 5%	1330
December	1st to 10th	Day	77% 4 9% 8% 3	1330
	11th to 20th	Day	82% 2 9% 4 2	1667
	21st to end	Day	87% 2 5% 4 1	2442
January	1st to 10th	Night	82% 3 6% 6% 2	4739
	11th to 20th	Night	74% 6% 5% 9% 5%	4528
	21st to end	Night	73% 4 10% 6% 6% 1	4884
February	1st to 10th	Night	80% 3 6% 7% 3	2660
	11th to 20th	Night	74% 3 8% 10% 4	2376
	21st to end	Night	64% 5% 7% 16% 7% 1	1884
March	1st to 10th	Night	69% 4 10% 12% 5% 1	3735
	11th to 20th	Night	74% 3 9% 9% 4 1	3557
	21st to end	Night	68% 3 8% 14% 6%	3674
April	1st to 10th	Night	69% 3 6% 14% 8%	1895
	11th to 20th	Night	63% 2 9% 18% 7% 1	1688
	21st to end	Night	64% 4 8% 16% 8% 1	1710
May	1st to 10th	Night	74% 2 11% 9% 3 1	2695
	11th to 20th	Night	75% 2 6% 12% 4	2301
	21st to end	Night	70% 3 8% 13% 6%	2413
June	1st to 10th	Night	69% 5% 10% 11% 5%	1330
	11th to 20th	Night	63% 3 12% 17% 5%	1330
	21st to end	Night	61% 4 11% 17% 6% 1	1330
July	1st to 10th	Night	59% 3 14% 20% 3	2186
	11th to 20th	Night	57% 4 13% 18% 7%	2178
	21st to end	Night	49% 3 17% 27% 4	2633
August	1st to 10th	Night	50% 5% 16% 25% 4	2505
	11th to 20th	Night	47% 4 16% 22% 11% 1	2813
	21st to end	Night	49% 2 15% 28% 6%	3134
September	1st to 10th	Night	51% 4 13% 22% 9% 1	1881
	11th to 20th	Night	57% 4 12% 18% 8%	2090
	21st to end	Night	56% 5% 14% 18% 7%	2090
October	1st to 10th	Night	64% 3 13% 14% 5%	3576
	11th to 20th	Night	65% 3 14% 13% 5%	4033
	21st to end	Night	65% 3 13% 13% 7% 1	4467
November	1st to 10th	Night	71% 4 9% 11% 5%	2568
	11th to 20th	Night	71% 5% 9% 12% 2	2709
	21st to end	Night	73% 5% 8% 8% 5%	2850
December	1st to 10th	Night	78% 4 7% 9% 2	2850
	11th to 20th	Night	90% 2 4 3 1	3533
	21st to end	Night	82% 3 6% 7% 2	5225

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	28% 15% 34% 19% 5%	370
	11th to 20th	Day	26% 17% 35% 18% 3	370
	21st to end	Day	29% 20% 30% 18% 2	407
February	1st to 10th	Day	26% 21% 32% 16% 5%	370
	11th to 20th	Day	25% 22% 34% 15% 3 1	366
	21st to end	Day	19% 18% 39% 16% 5% 3	307
March	1st to 10th	Day	25% 12% 38% 17% 6% 1	370
	11th to 20th	Day	27% 15% 24% 21% 11% 2	370
	21st to end	Day	34% 13% 27% 18% 6% 2	443
April	1st to 10th	Day	28% 12% 33% 20% 6% 1	464
	11th to 20th	Day	32% 8% 26% 24% 7% 3	639
	21st to end	Day	31% 8% 28% 24% 8% 1	650
May	1st to 10th	Day	35% 6% 22% 22% 11% 3	653
	11th to 20th	Day	28% 5% 26% 25% 14% 3	674
	21st to end	Day	34% 6% 23% 26% 9% 1	735
June	1st to 10th	Day	38% 6% 20% 22% 10% 4	680
	11th to 20th	Day	31% 5% 21% 27% 14% 3	680
	21st to end	Day	27% 3 24% 28% 15% 4	680
July	1st to 10th	Day	27% 4 23% 31% 11% 4	670
	11th to 20th	Day	24% 3 22% 28% 21% 2	668
	21st to end	Day	24% 4 22% 33% 15% 1	740
August	1st to 10th	Day	27% 6% 19% 30% 14% 4	675
	11th to 20th	Day	23% 4 21% 29% 20% 3	667
	21st to end	Day	27% 5% 21% 26% 17% 5%	748
September	1st to 10th	Day	26% 8% 25% 26% 11% 3	514
	11th to 20th	Day	35% 9% 23% 25% 7% 1	390
	21st to end	Day	27% 9% 35% 21% 7% 2	390
October	1st to 10th	Day	27% 12% 34% 19% 7% 1	390
	11th to 20th	Day	37% 10% 24% 16% 11% 2	390
	21st to end	Day	34% 16% 26% 17% 6% 2	429
November	1st to 10th	Day	40% 13% 31% 13% 3	395
	11th to 20th	Day	34% 19% 24% 17% 6% 1	370
	21st to end	Day	34% 17% 34% 14% 2	370
December	1st to 10th	Day	29% 14% 32% 18% 6%	370
	11th to 20th	Day	32% 24% 26% 16% 2	370
	21st to end	Day	28% 19% 31% 17% 5% 1	407
January	1st to 10th	Night	28% 18% 29% 19% 5% 1	850
	11th to 20th	Night	27% 17% 37% 14% 5%	850
	21st to end	Night	25% 19% 35% 17% 4	935
February	1st to 10th	Night	28% 20% 31% 18% 4 1	850
	11th to 20th	Night	30% 17% 33% 15% 3 1	814
	21st to end	Night	23% 12% 37% 19% 7% 2	628
March	1st to 10th	Night	27% 16% 32% 19% 5% 1	760
	11th to 20th	Night	25% 10% 30% 24% 10% 1	621
	21st to end	Night	34% 13% 26% 22% 5%	627
April	1st to 10th	Night	32% 11% 31% 19% 6% 1	570
	11th to 20th	Night	32% 8% 28% 21% 10% 1	564
	21st to end	Night	35% 5% 25% 29% 5% 1	570
May	1st to 10th	Night	37% 5% 19% 27% 11% 2	570
	11th to 20th	Night	38% 5% 19% 24% 12% 2	562
	21st to end	Night	35% 5% 24% 26% 8% 1	616
June	1st to 10th	Night	38% 5% 17% 28% 10% 1	570
	11th to 20th	Night	36% 4 18% 26% 14% 2	570
	21st to end	Night	32% 5% 21% 26% 14% 1	570
July	1st to 10th	Night	28% 3 22% 34% 11% 2	556
	11th to 20th	Night	24% 3 26% 36% 11% 1	552
	21st to end	Night	26% 4 23% 33% 13% 1	623
August	1st to 10th	Night	26% 4 20% 35% 15% 1	568
	11th to 20th	Night	24% 3 23% 32% 17% 1	562
	21st to end	Night	27% 4 19% 31% 17% 2	627
September	1st to 10th	Night	27% 5% 26% 31% 11% 1	570
	11th to 20th	Night	32% 9% 24% 29% 6%	570
	21st to end	Night	32% 7% 31% 23% 6% 1	570
October	1st to 10th	Night	36% 8% 28% 22% 7% 1	600
	11th to 20th	Night	35% 9% 23% 23% 9% 1	822
	21st to end	Night	40% 13% 21% 19% 6% 1	946
November	1st to 10th	Night	35% 16% 28% 17% 3	880
	11th to 20th	Night	35% 12% 28% 17% 6% 1	853
	21st to end	Night	34% 17% 31% 15% 3	850
December	1st to 10th	Night	32% 14% 29% 19% 5% 1	850
	11th to 20th	Night	36% 17% 30% 14% 4	850
	21st to end	Night	26% 19% 30% 18% 6% 1	935

Page generated at 2024-11-08 07:44:47. Version ac07

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