Pte. au Baril
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Pte. au Baril clear sky chart from 2005-11-06 to 2024-01-12.

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	16% 10% 4 7% 6% 3 4 5% 5% 7% 34%	74706
	Night	17% 12% 4 7% 6% 3 4 4 5% 6% 30%	75005
Transparency	Day	49% 7% 12% 21% 10% 1	74408
	Night	55% 6% 12% 18% 9% 1	74837
Seeing	Day	20% 13% 31% 24% 10% 2	13970
	Night	23% 12% 28% 25% 10% 1	23241

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	16% 19% 8% 12% 7% 3 4 4 4 5% 17%	1328
	11th to 20th	Day	15% 19% 7% 8% 6% 4 4 4 5% 7% 22%	1413
	21st to end	Day	15% 15% 6% 10% 8% 4 5% 5% 4 5% 23%	1782
February	1st to 10th	Day	15% 17% 6% 11% 7% 3 5% 4 4 6% 22%	1620
	11th to 20th	Day	14% 13% 7% 10% 7% 3 4 4 4 6% 29%	1573
	21st to end	Day	15% 16% 6% 11% 6% 3 3 4 5% 4 26%	1390
March	1st to 10th	Day	14% 10% 5% 9% 6% 3 5% 5% 4 6% 33%	1936
	11th to 20th	Day	13% 11% 4 8% 5% 4 5% 5% 6% 6% 34%	1980
	21st to end	Day	16% 9% 3 7% 5% 3 3 4 5% 7% 38%	2178
April	1st to 10th	Day	19% 10% 5% 5% 6% 4 5% 5% 5% 6% 30%	2101
	11th to 20th	Day	19% 8% 3 5% 5% 3 4 4 4 6% 38%	2294
	21st to end	Day	20% 9% 4 6% 5% 2 4 4 4 6% 36%	2340
May	1st to 10th	Day	19% 6% 3 5% 5% 3 4 5% 5% 7% 37%	2340
	11th to 20th	Day	17% 7% 3 5% 4 2 5% 5% 6% 7% 40%	2478
	21st to end	Day	13% 5% 2 5% 5% 3 5% 5% 5% 9% 43%	2725
June	1st to 10th	Day	16% 6% 3 5% 6% 3 4 5% 6% 7% 39%	2656
	11th to 20th	Day	12% 5% 2 6% 6% 3 5% 5% 6% 8% 42%	2700
	21st to end	Day	15% 7% 3 5% 6% 3 5% 5% 6% 8% 38%	2700
July	1st to 10th	Day	10% 4 2 5% 5% 3 4 5% 6% 9% 48%	2700
	11th to 20th	Day	11% 5% 3 5% 5% 3 5% 5% 6% 9% 45%	2695
	21st to end	Day	11% 5% 2 5% 5% 3 5% 5% 7% 9% 45%	2605
August	1st to 10th	Day	11% 6% 2 5% 5% 3 4 5% 5% 9% 45%	2327
	11th to 20th	Day	12% 5% 2 5% 4 3 5% 6% 6% 9% 42%	2303
	21st to end	Day	13% 6% 3 5% 6% 3 4 5% 6% 8% 41%	2543
September	1st to 10th	Day	13% 7% 2 5% 5% 3 5% 5% 7% 7% 42%	2160
	11th to 20th	Day	15% 5% 2 4 4 3 5% 5% 6% 8% 44%	2011
	21st to end	Day	21% 6% 3 5% 6% 3 4 4 4 6% 38%	1973
October	1st to 10th	Day	19% 8% 3 7% 6% 4 4 5% 4 7% 34%	1800
	11th to 20th	Day	27% 11% 4 8% 5% 4 5% 4 4 5% 25%	1800
	21st to end	Day	29% 12% 3 7% 6% 4 4 3 5% 5% 22%	1926
November	1st to 10th	Day	22% 13% 4 6% 6% 3 4 4 5% 7% 26%	1557
	11th to 20th	Day	19% 15% 5% 7% 7% 4 5% 6% 5% 6% 21%	1520
	21st to end	Day	25% 19% 5% 7% 6% 5% 5% 4 4 5% 15%	1520
December	1st to 10th	Day	18% 23% 7% 9% 6% 3 4 4 4 6% 15%	1520
	11th to 20th	Day	21% 20% 7% 9% 6% 3 4 4 3 4 19%	1781
	21st to end	Day	23% 20% 6% 12% 8% 4 3 4 3 4 13%	2431
January	1st to 10th	Night	16% 20% 8% 11% 7% 3 5% 4 3 4 17%	2838
	11th to 20th	Night	18% 18% 6% 10% 7% 3 4 3 5% 5% 20%	2570
	21st to end	Night	15% 14% 6% 11% 7% 3 5% 5% 5% 5% 24%	2574
February	1st to 10th	Night	13% 17% 7% 11% 7% 4 6% 4 5% 6% 21%	2340
	11th to 20th	Night	13% 15% 6% 11% 6% 4 5% 4 4 5% 27%	2273
	21st to end	Night	17% 13% 6% 9% 8% 4 4 4 5% 5% 25%	1866
March	1st to 10th	Night	13% 12% 5% 6% 5% 3 4 4 5% 7% 36%	2011
	11th to 20th	Night	14% 11% 5% 7% 6% 4 4 5% 5% 5% 35%	1979
	21st to end	Night	15% 9% 4 8% 6% 3 3 3 5% 6% 39%	2178
April	1st to 10th	Night	22% 11% 4 7% 5% 3 4 3 6% 6% 30%	1858
	11th to 20th	Night	19% 8% 3 7% 6% 3 4 3 4 7% 37%	1631
	21st to end	Night	20% 9% 4 8% 7% 3 4 4 4 7% 30%	1620
May	1st to 10th	Night	16% 7% 2 5% 5% 3 5% 6% 6% 9% 37%	1619
	11th to 20th	Night	15% 6% 2 5% 5% 3 4 5% 7% 8% 40%	1415
	21st to end	Night	10% 5% 2 6% 5% 3 5% 6% 6% 9% 43%	1550
June	1st to 10th	Night	14% 7% 3 6% 6% 3 4 5% 5% 8% 38%	1300
	11th to 20th	Night	12% 5% 2 4 4 3 5% 4 7% 10% 43%	1260
	21st to end	Night	12% 6% 2 5% 5% 3 5% 5% 5% 9% 42%	1260
July	1st to 10th	Night	9% 4 1 4 3 3 5% 6% 6% 9% 49%	1260
	11th to 20th	Night	9% 6% 3 5% 4 3 4 5% 7% 7% 47%	1264
	21st to end	Night	10% 5% 3 5% 5% 4 5% 5% 6% 8% 47%	1709
August	1st to 10th	Night	10% 6% 2 5% 4 3 4 5% 5% 9% 47%	1611
	11th to 20th	Night	11% 4 2 5% 6% 3 5% 5% 5% 8% 46%	1598
	21st to end	Night	14% 7% 2 4 6% 3 4 4 5% 7% 43%	1795
September	1st to 10th	Night	12% 4 2 4 5% 3 4 5% 7% 8% 47%	1800
	11th to 20th	Night	13% 6% 2 5% 3 3 5% 4 4 7% 47%	1947
	21st to end	Night	17% 7% 2 6% 5% 2 4 4 6% 7% 39%	1985
October	1st to 10th	Night	21% 8% 3 6% 5% 3 4 4 4 6% 35%	2160
	11th to 20th	Night	27% 9% 3 7% 7% 3 4 5% 5% 5% 25%	2160
	21st to end	Night	28% 11% 4 7% 5% 3 4 4 4 6% 23%	2427
November	1st to 10th	Night	23% 13% 4 7% 4 3 3 3 5% 6% 29%	2520
	11th to 20th	Night	19% 15% 5% 8% 6% 4 5% 5% 4 6% 23%	2660
	21st to end	Night	26% 19% 5% 7% 6% 4 4 5% 4 4 16%	2660
December	1st to 10th	Night	21% 22% 7% 9% 7% 4 4 5% 4 4 14%	2660
	11th to 20th	Night	21% 20% 6% 8% 6% 3 4 4 4 5% 19%	3411
	21st to end	Night	24% 21% 6% 11% 7% 3 4 3 3 4 14%	5236

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	70% 6% 10% 11% 3	1329
	11th to 20th	Day	64% 6% 10% 14% 5% 1	1413
	21st to end	Day	64% 6% 8% 12% 8% 1	1782
February	1st to 10th	Day	65% 6% 7% 16% 5%	1620
	11th to 20th	Day	57% 6% 11% 16% 9% 1	1582
	21st to end	Day	60% 6% 9% 18% 7%	1390
March	1st to 10th	Day	51% 7% 13% 15% 12% 1	1939
	11th to 20th	Day	50% 6% 11% 20% 10% 2	1980
	21st to end	Day	46% 6% 10% 19% 15% 3	2178
April	1st to 10th	Day	52% 7% 11% 17% 11% 1	2101
	11th to 20th	Day	47% 6% 8% 24% 14% 1	2294
	21st to end	Day	48% 6% 11% 19% 13% 3	2340
May	1st to 10th	Day	45% 6% 10% 22% 14% 3	2340
	11th to 20th	Day	41% 8% 10% 25% 15% 2	2482
	21st to end	Day	37% 8% 15% 23% 14% 3	2725
June	1st to 10th	Day	42% 7% 11% 26% 14% 1	2656
	11th to 20th	Day	38% 7% 11% 26% 17% 1	2700
	21st to end	Day	42% 10% 12% 24% 11% 1	2700
July	1st to 10th	Day	31% 8% 15% 29% 15% 2	2626
	11th to 20th	Day	34% 9% 14% 32% 11% 1	2614
	21st to end	Day	36% 9% 14% 28% 14% 1	2459
August	1st to 10th	Day	34% 9% 16% 29% 12% 1	2314
	11th to 20th	Day	35% 10% 17% 27% 10%	2303
	21st to end	Day	40% 8% 16% 24% 11% 1	2543
September	1st to 10th	Day	39% 8% 13% 27% 11% 1	2160
	11th to 20th	Day	36% 8% 15% 31% 9% 1	2011
	21st to end	Day	47% 8% 13% 25% 7%	1973
October	1st to 10th	Day	49% 8% 13% 18% 11% 1	1800
	11th to 20th	Day	62% 5% 13% 14% 6%	1800
	21st to end	Day	64% 6% 12% 12% 5%	1926
November	1st to 10th	Day	57% 7% 13% 17% 5%	1557
	11th to 20th	Day	63% 7% 14% 10% 5% 1	1520
	21st to end	Day	71% 7% 13% 7% 2	1520
December	1st to 10th	Day	71% 6% 11% 10% 2 1	1520
	11th to 20th	Day	70% 5% 11% 11% 3	1780
	21st to end	Day	76% 7% 7% 7% 2	2431
January	1st to 10th	Night	72% 5% 9% 10% 4	2838
	11th to 20th	Night	68% 5% 11% 11% 5% 1	2570
	21st to end	Night	62% 5% 9% 15% 8% 1	2574
February	1st to 10th	Night	64% 5% 11% 15% 5% 1	2340
	11th to 20th	Night	60% 5% 13% 15% 7% 1	2275
	21st to end	Night	61% 5% 12% 15% 7% 1	1866
March	1st to 10th	Night	48% 5% 14% 18% 14% 1	2021
	11th to 20th	Night	50% 6% 10% 20% 11% 2	1980
	21st to end	Night	47% 5% 10% 20% 15% 3	2178
April	1st to 10th	Night	55% 5% 8% 19% 12% 2	1858
	11th to 20th	Night	48% 5% 8% 21% 17% 2	1631
	21st to end	Night	54% 5% 10% 15% 14% 2	1620
May	1st to 10th	Night	43% 6% 11% 22% 14% 3	1619
	11th to 20th	Night	40% 5% 10% 25% 17% 3	1416
	21st to end	Night	36% 7% 15% 22% 16% 4	1551
June	1st to 10th	Night	42% 6% 11% 23% 15% 2	1300
	11th to 20th	Night	35% 6% 15% 25% 19% 1	1260
	21st to end	Night	39% 7% 16% 24% 13% 2	1260
July	1st to 10th	Night	29% 7% 13% 29% 19% 4	1225
	11th to 20th	Night	33% 7% 15% 28% 15% 2	1222
	21st to end	Night	35% 8% 14% 28% 14% 1	1614
August	1st to 10th	Night	34% 7% 18% 28% 13% 1	1600
	11th to 20th	Night	35% 8% 17% 26% 13% 1	1598
	21st to end	Night	39% 7% 15% 27% 11% 1	1795
September	1st to 10th	Night	34% 7% 16% 28% 14% 2	1800
	11th to 20th	Night	36% 6% 16% 31% 10%	1947
	21st to end	Night	43% 6% 16% 27% 8%	1985
October	1st to 10th	Night	52% 5% 12% 19% 12%	2160
	11th to 20th	Night	62% 6% 12% 16% 4	2160
	21st to end	Night	64% 4 11% 13% 6%	2427
November	1st to 10th	Night	55% 7% 13% 20% 6%	2520
	11th to 20th	Night	62% 6% 15% 13% 4 1	2660
	21st to end	Night	71% 6% 13% 9% 1	2660
December	1st to 10th	Night	74% 6% 10% 8% 2	2660
	11th to 20th	Night	68% 6% 10% 12% 4	3411
	21st to end	Night	76% 5% 9% 8% 2	5236

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	25% 22% 28% 19% 5% 1	180
	11th to 20th	Day	23% 19% 30% 22% 5% 1	208
	21st to end	Day	28% 14% 35% 17% 6% 1	264
February	1st to 10th	Day	31% 25% 30% 10% 3	240
	11th to 20th	Day	22% 20% 45% 11% 1	240
	21st to end	Day	33% 26% 32% 10%	198
March	1st to 10th	Day	21% 20% 36% 18% 3 1	379
	11th to 20th	Day	19% 20% 36% 19% 5% 1	420
	21st to end	Day	26% 16% 33% 20% 5% 1	462
April	1st to 10th	Day	22% 16% 33% 20% 9%	420
	11th to 20th	Day	27% 16% 27% 17% 9% 3	412
	21st to end	Day	24% 16% 33% 19% 7% 1	420
May	1st to 10th	Day	23% 8% 35% 24% 8% 2	423
	11th to 20th	Day	18% 13% 30% 23% 13% 3	447
	21st to end	Day	16% 10% 30% 28% 12% 2	485
June	1st to 10th	Day	16% 10% 33% 31% 9% 1	586
	11th to 20th	Day	13% 10% 35% 27% 12% 2	630
	21st to end	Day	16% 10% 30% 33% 9% 2	630
July	1st to 10th	Day	10% 6% 30% 36% 15% 2	621
	11th to 20th	Day	12% 7% 29% 33% 15% 4	613
	21st to end	Day	11% 5% 32% 34% 14% 3	488
August	1st to 10th	Day	15% 6% 25% 32% 16% 6%	446
	11th to 20th	Day	12% 7% 21% 32% 18% 9%	439
	21st to end	Day	17% 9% 27% 27% 14% 5%	495
September	1st to 10th	Day	15% 11% 29% 26% 15% 5%	450
	11th to 20th	Day	15% 8% 28% 28% 17% 4	450
	21st to end	Day	24% 8% 24% 26% 16% 2	450
October	1st to 10th	Day	23% 14% 27% 22% 12% 2	450
	11th to 20th	Day	29% 15% 33% 18% 4	450
	21st to end	Day	34% 18% 30% 16% 1 1	441
November	1st to 10th	Day	30% 18% 33% 15% 3	215
	11th to 20th	Day	20% 25% 40% 13% 2 1	180
	21st to end	Day	35% 21% 27% 15% 2 1	180
December	1st to 10th	Day	30% 21% 32% 14% 4	180
	11th to 20th	Day	33% 22% 30% 10% 4	180
	21st to end	Day	34% 21% 31% 12% 3	198
January	1st to 10th	Night	26% 18% 30% 21% 5% 1	950
	11th to 20th	Night	28% 15% 30% 21% 5%	862
	21st to end	Night	21% 10% 33% 26% 8% 1	792
February	1st to 10th	Night	23% 19% 34% 19% 4	720
	11th to 20th	Night	21% 14% 34% 24% 6%	703
	21st to end	Night	24% 17% 31% 24% 4 1	592
March	1st to 10th	Night	19% 16% 35% 25% 5%	720
	11th to 20th	Night	22% 13% 35% 23% 6% 1	720
	21st to end	Night	19% 11% 33% 27% 10% 1	792
April	1st to 10th	Night	25% 11% 32% 25% 7%	720
	11th to 20th	Night	23% 11% 27% 27% 11% 1	567
	21st to end	Night	24% 10% 27% 24% 14%	540
May	1st to 10th	Night	19% 6% 25% 34% 13% 2	539
	11th to 20th	Night	17% 6% 27% 35% 14% 1	354
	21st to end	Night	12% 5% 32% 35% 16% 1	389
June	1st to 10th	Night	15% 5% 29% 38% 13% 1	360
	11th to 20th	Night	16% 8% 20% 36% 19% 1	360
	21st to end	Night	15% 4 23% 35% 21% 2	360
July	1st to 10th	Night	10% 4 18% 47% 21% 1	350
	11th to 20th	Night	12% 2 23% 35% 24% 2	348
	21st to end	Night	11% 6% 24% 35% 22% 2	529
August	1st to 10th	Night	12% 4 19% 38% 23% 5%	537
	11th to 20th	Night	12% 5% 19% 34% 26% 5%	534
	21st to end	Night	17% 7% 21% 30% 22% 2	607
September	1st to 10th	Night	14% 6% 26% 30% 19% 5%	720
	11th to 20th	Night	15% 7% 25% 30% 18% 5%	720
	21st to end	Night	18% 8% 24% 30% 17% 4	720
October	1st to 10th	Night	25% 10% 28% 24% 12% 2	720
	11th to 20th	Night	32% 13% 26% 21% 7% 1	720
	21st to end	Night	33% 15% 29% 19% 4	792
November	1st to 10th	Night	32% 12% 27% 21% 8%	740
	11th to 20th	Night	27% 18% 31% 18% 6%	760
	21st to end	Night	37% 14% 28% 17% 3	760
December	1st to 10th	Night	34% 18% 30% 14% 4	760
	11th to 20th	Night	30% 19% 31% 15% 4 1	839
	21st to end	Night	34% 15% 31% 18% 3	1045

Page generated at 2024-01-09 07:14:40. Version ac07

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