Lewisporte
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lewisporte clear sky chart from 2005-11-06 to 2024-11-04.

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% 14% 4 9% 5% 5% 4 3 5% 6% 23%	101807
	Night	21% 14% 5% 9% 5% 5% 4 3 5% 6% 23%	97355
Transparency	Day	61% 7% 12% 14% 5%	105252
	Night	61% 7% 12% 13% 5%	102023
Seeing	Day	29% 15% 29% 19% 7% 1	18129
	Night	29% 15% 31% 19% 5%	24847

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	13% 17% 7% 16% 9% 7% 5% 3 5% 4 15%	2216
	11th to 20th	Day	18% 13% 6% 14% 7% 6% 5% 4 5% 5% 17%	2503
	21st to end	Day	11% 12% 6% 11% 9% 8% 6% 4 6% 6% 21%	2783
February	1st to 10th	Day	17% 14% 5% 11% 8% 5% 6% 4 7% 5% 18%	1520
	11th to 20th	Day	19% 19% 5% 11% 7% 4 5% 4 5% 4 17%	1712
	21st to end	Day	13% 13% 5% 12% 8% 6% 6% 3 4 5% 23%	1570
March	1st to 10th	Day	17% 14% 4 13% 8% 6% 5% 3 4 5% 21%	3114
	11th to 20th	Day	22% 19% 8% 12% 7% 5% 4 3 4 4 12%	3380
	21st to end	Day	26% 18% 6% 10% 5% 3 3 2 3 4 19%	3967
April	1st to 10th	Day	19% 19% 6% 11% 6% 5% 5% 4 4 5% 17%	2280
	11th to 20th	Day	23% 17% 6% 7% 4 4 3 3 4 6% 23%	2428
	21st to end	Day	21% 20% 4 8% 5% 4 4 4 4 5% 21%	2470
May	1st to 10th	Day	30% 21% 7% 7% 4 3 3 2 3 5% 15%	4255
	11th to 20th	Day	23% 17% 6% 10% 5% 4 4 3 4 5% 19%	4541
	21st to end	Day	28% 16% 4 7% 4 4 3 3 4 5% 21%	5173
June	1st to 10th	Day	32% 15% 3 7% 5% 4 4 4 4 4 16%	2850
	11th to 20th	Day	28% 12% 3 6% 4 4 4 3 5% 5% 25%	2850
	21st to end	Day	24% 11% 3 6% 5% 5% 5% 4 5% 7% 25%	2850
July	1st to 10th	Day	19% 12% 3 8% 5% 5% 5% 4 6% 7% 26%	4750
	11th to 20th	Day	14% 8% 3 8% 6% 5% 6% 5% 7% 9% 28%	4698
	21st to end	Day	15% 7% 2 6% 5% 5% 5% 4 7% 8% 36%	4815
August	1st to 10th	Day	21% 10% 3 9% 5% 5% 6% 4 6% 8% 23%	4424
	11th to 20th	Day	19% 8% 3 6% 4 4 4 3 5% 6% 38%	4051
	21st to end	Day	20% 8% 2 6% 4 4 4 4 6% 8% 34%	4532
September	1st to 10th	Day	22% 7% 3 6% 4 4 5% 3 5% 8% 33%	2281
	11th to 20th	Day	28% 9% 3 6% 5% 3 4 3 5% 6% 28%	2090
	21st to end	Day	20% 10% 3 7% 4 4 4 3 5% 8% 30%	2090
October	1st to 10th	Day	22% 11% 3 7% 4 4 4 3 5% 6% 31%	2047
	11th to 20th	Day	23% 13% 3 9% 5% 4 4 4 6% 6% 22%	1736
	21st to end	Day	25% 19% 4 7% 5% 5% 4 3 4 4 19%	1881
November	1st to 10th	Day	23% 18% 4 9% 5% 4 5% 4 5% 5% 18%	1697
	11th to 20th	Day	20% 18% 5% 8% 5% 3 4 3 4 6% 23%	1483
	21st to end	Day	22% 17% 5% 10% 5% 4 4 2 4 6% 20%	1330
December	1st to 10th	Day	20% 18% 6% 11% 6% 5% 4 3 5% 5% 17%	1330
	11th to 20th	Day	25% 15% 5% 13% 6% 4 5% 4 4 6% 14%	1668
	21st to end	Day	21% 19% 5% 13% 7% 4 4 3 5% 5% 13%	2442
January	1st to 10th	Night	13% 18% 6% 15% 7% 8% 5% 3 4 5% 16%	4739
	11th to 20th	Night	12% 13% 6% 13% 7% 6% 5% 4 6% 7% 22%	4463
	21st to end	Night	10% 12% 5% 13% 8% 7% 8% 3 5% 6% 23%	4884
February	1st to 10th	Night	17% 12% 5% 12% 8% 6% 5% 4 5% 6% 20%	2660
	11th to 20th	Night	20% 17% 5% 10% 6% 5% 5% 4 4 5% 19%	2352
	21st to end	Night	15% 13% 5% 9% 7% 5% 6% 4 5% 6% 26%	1884
March	1st to 10th	Night	20% 14% 4 12% 5% 5% 5% 5% 5% 5% 20%	3726
	11th to 20th	Night	19% 19% 6% 12% 7% 5% 5% 4 4 5% 14%	3578
	21st to end	Night	26% 14% 4 9% 4 3 4 3 5% 6% 21%	3662
April	1st to 10th	Night	24% 18% 6% 7% 4 4 3 3 5% 5% 21%	1900
	11th to 20th	Night	25% 17% 5% 6% 4 3 4 3 4 5% 24%	1701
	21st to end	Night	25% 18% 4 7% 4 3 3 3 4 5% 25%	1710
May	1st to 10th	Night	33% 20% 6% 8% 4 3 2 2 3 5% 13%	2690
	11th to 20th	Night	25% 19% 9% 12% 4 3 2 2 3 4 16%	2360
	21st to end	Night	30% 14% 6% 6% 4 3 3 4 5% 5% 20%	2412
June	1st to 10th	Night	34% 13% 3 7% 5% 3 4 3 6% 6% 16%	1330
	11th to 20th	Night	32% 9% 3 4 4 3 4 4 6% 7% 24%	1330
	21st to end	Night	23% 12% 3 8% 6% 5% 5% 3 4 6% 25%	1330
July	1st to 10th	Night	23% 11% 4 7% 4 5% 5% 4 6% 6% 26%	2220
	11th to 20th	Night	14% 12% 3 9% 7% 5% 4 4 7% 7% 29%	2269
	21st to end	Night	16% 9% 3 7% 4 4 5% 3 5% 8% 38%	2750
August	1st to 10th	Night	15% 9% 3 8% 5% 5% 5% 5% 6% 8% 32%	2516
	11th to 20th	Night	16% 9% 4 7% 4 4 3 3 5% 7% 38%	2784
	21st to end	Night	21% 7% 3 6% 4 4 4 3 5% 6% 37%	3135
September	1st to 10th	Night	24% 8% 3 6% 3 3 3 3 4 6% 36%	1896
	11th to 20th	Night	24% 10% 3 6% 5% 4 4 3 5% 5% 31%	2090
	21st to end	Night	22% 11% 3 7% 4 3 5% 3 5% 7% 29%	2090
October	1st to 10th	Night	24% 11% 3 7% 4 4 3 3 5% 6% 29%	2133
	11th to 20th	Night	25% 12% 3 8% 4 4 4 3 5% 6% 26%	2441
	21st to end	Night	29% 17% 3 7% 4 3 4 3 3 5% 22%	2717
November	1st to 10th	Night	22% 16% 4 9% 6% 5% 5% 4 5% 6% 18%	2454
	11th to 20th	Night	23% 15% 5% 9% 5% 4 4 4 5% 6% 21%	2693
	21st to end	Night	19% 17% 7% 8% 6% 4 4 3 6% 6% 20%	2850
December	1st to 10th	Night	20% 18% 6% 12% 6% 5% 4 3 5% 5% 16%	2850
	11th to 20th	Night	28% 17% 6% 13% 6% 5% 4 2 4 4 12%	3531
	21st to end	Night	22% 15% 6% 11% 6% 5% 4 3 5% 6% 17%	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	65% 13% 11% 8% 3 1	2217
	11th to 20th	Day	65% 10% 10% 9% 6%	2503
	21st to end	Day	60% 10% 10% 12% 6% 2	2783
February	1st to 10th	Day	64% 8% 12% 10% 6% 1	1520
	11th to 20th	Day	68% 7% 11% 11% 4	1719
	21st to end	Day	61% 7% 9% 13% 8% 1	1570
March	1st to 10th	Day	63% 7% 9% 13% 6% 1	3118
	11th to 20th	Day	75% 6% 7% 7% 4	3380
	21st to end	Day	70% 5% 8% 12% 4	3967
April	1st to 10th	Day	69% 5% 9% 11% 5% 1	2280
	11th to 20th	Day	62% 5% 10% 14% 8% 1	2428
	21st to end	Day	65% 6% 8% 13% 8%	2470
May	1st to 10th	Day	73% 5% 10% 8% 3	4270
	11th to 20th	Day	66% 8% 9% 12% 5%	4545
	21st to end	Day	64% 6% 9% 14% 6%	5173
June	1st to 10th	Day	70% 6% 9% 11% 4	2850
	11th to 20th	Day	60% 7% 12% 15% 5% 1	2850
	21st to end	Day	59% 9% 12% 13% 7% 1	2850
July	1st to 10th	Day	57% 7% 12% 18% 7%	4675
	11th to 20th	Day	50% 9% 17% 19% 5%	4616
	21st to end	Day	42% 10% 17% 26% 6%	4662
August	1st to 10th	Day	57% 8% 16% 16% 3	4410
	11th to 20th	Day	46% 7% 15% 19% 12% 1	4090
	21st to end	Day	47% 7% 16% 24% 6%	4532
September	1st to 10th	Day	48% 7% 12% 23% 8% 1	2281
	11th to 20th	Day	57% 7% 13% 17% 6%	2090
	21st to end	Day	52% 6% 18% 17% 6%	2090
October	1st to 10th	Day	58% 7% 12% 16% 6%	3401
	11th to 20th	Day	60% 8% 11% 15% 6%	2871
	21st to end	Day	66% 6% 9% 10% 8% 1	3092
November	1st to 10th	Day	67% 7% 12% 10% 3	1697
	11th to 20th	Day	63% 7% 11% 11% 6% 1	1483
	21st to end	Day	66% 8% 13% 8% 5% 1	1330
December	1st to 10th	Day	69% 7% 11% 9% 3	1330
	11th to 20th	Day	71% 8% 12% 7% 2	1667
	21st to end	Day	73% 8% 10% 8% 2	2442
January	1st to 10th	Night	63% 12% 12% 9% 3	4739
	11th to 20th	Night	59% 8% 13% 13% 6%	4463
	21st to end	Night	58% 10% 14% 10% 5% 2	4884
February	1st to 10th	Night	63% 7% 12% 11% 6%	2660
	11th to 20th	Night	67% 7% 10% 12% 4	2356
	21st to end	Night	56% 8% 10% 16% 8% 1	1884
March	1st to 10th	Night	63% 7% 11% 13% 5% 1	3735
	11th to 20th	Night	71% 8% 9% 8% 4 1	3579
	21st to end	Night	62% 6% 12% 14% 5% 1	3662
April	1st to 10th	Night	65% 5% 9% 13% 8% 1	1900
	11th to 20th	Night	63% 4 10% 17% 6% 1	1701
	21st to end	Night	63% 6% 8% 13% 9% 1	1710
May	1st to 10th	Night	74% 4 10% 8% 3	2695
	11th to 20th	Night	72% 5% 8% 10% 4	2361
	21st to end	Night	64% 8% 11% 12% 6%	2413
June	1st to 10th	Night	68% 7% 12% 9% 4	1330
	11th to 20th	Night	58% 8% 15% 14% 5%	1330
	21st to end	Night	60% 8% 11% 14% 7% 1	1330
July	1st to 10th	Night	57% 7% 14% 18% 4	2186
	11th to 20th	Night	52% 9% 15% 16% 7%	2227
	21st to end	Night	45% 7% 17% 26% 5%	2663
August	1st to 10th	Night	47% 10% 18% 22% 4	2505
	11th to 20th	Night	45% 7% 17% 21% 9% 1	2811
	21st to end	Night	47% 6% 16% 26% 5%	3134
September	1st to 10th	Night	49% 6% 13% 22% 9% 1	1896
	11th to 20th	Night	55% 6% 13% 17% 9% 1	2090
	21st to end	Night	54% 7% 13% 17% 7%	2090
October	1st to 10th	Night	60% 6% 15% 13% 5% 1	3562
	11th to 20th	Night	58% 8% 15% 13% 6%	4055
	21st to end	Night	58% 5% 12% 15% 8% 1	4467
November	1st to 10th	Night	65% 8% 11% 11% 4	2454
	11th to 20th	Night	64% 7% 13% 13% 3	2693
	21st to end	Night	64% 7% 12% 10% 5%	2850
December	1st to 10th	Night	70% 7% 10% 10% 3	2850
	11th to 20th	Night	77% 6% 9% 6% 2	3533
	21st to end	Night	67% 10% 13% 9% 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	24% 22% 35% 14% 5%	370
	11th to 20th	Day	23% 24% 35% 16% 3	370
	21st to end	Day	28% 19% 31% 17% 4	407
February	1st to 10th	Day	26% 26% 28% 16% 4	370
	11th to 20th	Day	27% 24% 34% 11% 2 1	366
	21st to end	Day	20% 23% 37% 15% 3 1	307
March	1st to 10th	Day	24% 21% 39% 12% 4 1	370
	11th to 20th	Day	28% 16% 28% 17% 8% 2	370
	21st to end	Day	37% 21% 22% 15% 3 2	450
April	1st to 10th	Day	29% 21% 30% 17% 3	460
	11th to 20th	Day	34% 13% 28% 19% 5% 1	626
	21st to end	Day	32% 17% 30% 18% 3	650
May	1st to 10th	Day	38% 12% 24% 17% 6% 2	653
	11th to 20th	Day	30% 13% 28% 18% 9% 2	674
	21st to end	Day	34% 13% 30% 19% 4 1	735
June	1st to 10th	Day	41% 11% 24% 15% 9% 1	680
	11th to 20th	Day	33% 11% 25% 20% 9% 1	680
	21st to end	Day	28% 10% 27% 22% 11% 3	680
July	1st to 10th	Day	29% 10% 26% 23% 9% 3	670
	11th to 20th	Day	21% 11% 28% 28% 10% 1	668
	21st to end	Day	23% 10% 25% 31% 10% 1	740
August	1st to 10th	Day	25% 9% 28% 25% 10% 2	675
	11th to 20th	Day	22% 7% 28% 24% 16% 2	667
	21st to end	Day	24% 8% 27% 25% 12% 3	748
September	1st to 10th	Day	25% 12% 31% 23% 9% 1	493
	11th to 20th	Day	36% 12% 28% 20% 4 1	390
	21st to end	Day	23% 20% 34% 16% 5% 2	390
October	1st to 10th	Day	25% 19% 33% 17% 5% 2	390
	11th to 20th	Day	35% 11% 26% 18% 7% 3	390
	21st to end	Day	33% 21% 25% 14% 6% 1	429
November	1st to 10th	Day	37% 17% 29% 13% 2	374
	11th to 20th	Day	33% 22% 24% 15% 5% 1	370
	21st to end	Day	36% 20% 31% 12% 1	370
December	1st to 10th	Day	27% 16% 33% 17% 6% 1	370
	11th to 20th	Day	30% 25% 29% 13% 3	370
	21st to end	Day	24% 21% 31% 18% 5% 1	407
January	1st to 10th	Night	26% 20% 31% 18% 5% 1	850
	11th to 20th	Night	23% 24% 34% 16% 3	850
	21st to end	Night	24% 20% 38% 15% 3	935
February	1st to 10th	Night	26% 20% 35% 16% 3	850
	11th to 20th	Night	29% 22% 34% 12% 2	804
	21st to end	Night	21% 15% 40% 16% 6% 1	628
March	1st to 10th	Night	28% 19% 34% 14% 5% 1	760
	11th to 20th	Night	24% 16% 29% 23% 7%	630
	21st to end	Night	32% 17% 29% 17% 4	627
April	1st to 10th	Night	32% 19% 28% 16% 4 1	570
	11th to 20th	Night	32% 11% 33% 18% 5% 1	564
	21st to end	Night	32% 12% 34% 19% 2	570
May	1st to 10th	Night	36% 10% 24% 22% 7% 1	570
	11th to 20th	Night	35% 11% 27% 19% 9%	562
	21st to end	Night	35% 11% 31% 18% 5%	616
June	1st to 10th	Night	40% 10% 22% 24% 3	570
	11th to 20th	Night	38% 8% 24% 24% 6% 1	570
	21st to end	Night	29% 9% 31% 22% 8%	570
July	1st to 10th	Night	25% 8% 33% 27% 7% 1	556
	11th to 20th	Night	22% 9% 31% 33% 5%	552
	21st to end	Night	24% 7% 30% 32% 7%	623
August	1st to 10th	Night	23% 6% 30% 30% 10%	568
	11th to 20th	Night	23% 6% 30% 31% 10%	562
	21st to end	Night	24% 8% 28% 31% 9% 1	627
September	1st to 10th	Night	27% 7% 34% 25% 6%	570
	11th to 20th	Night	29% 13% 31% 24% 3	570
	21st to end	Night	31% 12% 32% 21% 4	570
October	1st to 10th	Night	32% 11% 32% 21% 4 1	593
	11th to 20th	Night	33% 11% 29% 20% 7%	831
	21st to end	Night	38% 15% 25% 16% 5% 1	946
November	1st to 10th	Night	32% 20% 30% 15% 3	848
	11th to 20th	Night	33% 16% 31% 15% 5% 1	850
	21st to end	Night	32% 21% 32% 14% 2	850
December	1st to 10th	Night	29% 18% 34% 15% 5% 1	850
	11th to 20th	Night	33% 21% 32% 11% 2	850
	21st to end	Night	24% 20% 33% 17% 4 1	935

Page generated at 2024-11-02 00:47:50. Version ac07

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