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 2024-11-05.

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% 3 8% 5% 4 4 4 5% 7% 34%	101621
	Night	16% 13% 4 9% 5% 4 4 3 5% 6% 31%	97440
Transparency	Day	47% 8% 13% 22% 10% 1	105176
	Night	52% 6% 12% 19% 9% 1	101973
Seeing	Day	20% 13% 31% 24% 9% 2	15146
	Night	23% 12% 28% 25% 10% 1	24225

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% 23% 11% 12% 5% 4 3 3 4 4 16%	2208
	11th to 20th	Day	10% 18% 6% 18% 8% 6% 6% 4 5% 5% 14%	2452
	21st to end	Day	17% 21% 6% 13% 6% 5% 4 3 3 4 18%	3124
February	1st to 10th	Day	14% 18% 5% 12% 7% 5% 5% 3 4 6% 22%	1710
	11th to 20th	Day	13% 15% 6% 10% 6% 4 5% 3 5% 5% 29%	1663
	21st to end	Day	14% 17% 6% 12% 5% 4 3 4 5% 5% 27%	1475
March	1st to 10th	Day	19% 13% 4 9% 4 4 4 4 4 6% 29%	3367
	11th to 20th	Day	11% 16% 6% 10% 6% 5% 5% 3 6% 6% 28%	3480
	21st to end	Day	13% 12% 3 8% 5% 4 4 3 5% 6% 36%	3815
April	1st to 10th	Day	19% 11% 4 6% 5% 5% 4 4 5% 6% 30%	2218
	11th to 20th	Day	20% 9% 3 6% 5% 3 4 3 4 6% 37%	2423
	21st to end	Day	21% 9% 3 7% 4 3 4 3 4 6% 37%	2470
May	1st to 10th	Day	18% 6% 3 7% 5% 4 4 4 6% 8% 36%	4108
	11th to 20th	Day	13% 7% 2 6% 4 3 4 4 7% 9% 41%	4398
	21st to end	Day	18% 6% 2 6% 4 3 4 4 5% 7% 42%	4837
June	1st to 10th	Day	16% 7% 2 6% 5% 5% 4 4 6% 7% 38%	2804
	11th to 20th	Day	12% 5% 2 7% 5% 4 4 5% 6% 8% 42%	2850
	21st to end	Day	16% 8% 3 6% 5% 4 5% 4 6% 8% 37%	2850
July	1st to 10th	Day	15% 6% 2 7% 5% 5% 4 4 6% 8% 38%	4760
	11th to 20th	Day	11% 5% 2 5% 4 4 4 4 6% 8% 48%	4741
	21st to end	Day	10% 5% 2 5% 3 4 4 3 6% 7% 51%	4566
August	1st to 10th	Day	9% 6% 2 7% 4 5% 5% 4 6% 9% 41%	4104
	11th to 20th	Day	15% 6% 2 5% 3 3 5% 4 7% 9% 40%	4044
	21st to end	Day	9% 5% 2 6% 5% 4 5% 4 5% 8% 47%	4473
September	1st to 10th	Day	13% 7% 2 6% 4 4 5% 4 7% 6% 42%	2280
	11th to 20th	Day	14% 5% 2 4 4 4 4 4 6% 7% 46%	2122
	21st to end	Day	21% 6% 2 7% 4 4 4 3 4 6% 38%	2082
October	1st to 10th	Day	18% 8% 3 7% 5% 4 5% 3 4 7% 36%	1900
	11th to 20th	Day	25% 11% 4 8% 4 5% 5% 3 4 6% 26%	1900
	21st to end	Day	28% 12% 3 8% 5% 4 4 3 5% 5% 23%	2033
November	1st to 10th	Day	21% 14% 4 7% 5% 4 3 4 5% 7% 26%	1592
	11th to 20th	Day	18% 16% 5% 8% 6% 5% 4 4 5% 7% 21%	1520
	21st to end	Day	24% 20% 5% 8% 5% 6% 4 3 4 5% 15%	1520
December	1st to 10th	Day	17% 25% 6% 10% 5% 4 4 3 4 6% 15%	1520
	11th to 20th	Day	21% 21% 6% 10% 4 4 4 3 4 4 19%	1781
	21st to end	Day	23% 21% 6% 13% 6% 4 4 2 3 4 13%	2431
January	1st to 10th	Night	15% 21% 12% 14% 6% 5% 4 3 3 4 14%	4748
	11th to 20th	Night	13% 16% 6% 18% 7% 5% 4 4 6% 5% 15%	4496
	21st to end	Night	15% 21% 8% 14% 6% 4 4 3 3 4 18%	4532
February	1st to 10th	Night	13% 18% 6% 11% 6% 5% 5% 3 6% 6% 22%	2470
	11th to 20th	Night	12% 15% 6% 11% 6% 6% 3 3 4 5% 26%	2403
	21st to end	Night	16% 14% 5% 11% 7% 5% 4 3 5% 5% 25%	1979
March	1st to 10th	Night	14% 13% 4 8% 4 4 4 3 5% 7% 34%	3473
	11th to 20th	Night	11% 14% 5% 9% 5% 4 4 3 5% 5% 34%	3479
	21st to end	Night	13% 10% 3 9% 6% 5% 4 4 5% 6% 36%	3817
April	1st to 10th	Night	21% 12% 4 7% 4 4 3 3 6% 5% 30%	1961
	11th to 20th	Night	19% 9% 3 8% 4 4 3 3 5% 6% 37%	1722
	21st to end	Night	20% 9% 3 10% 5% 4 4 3 5% 6% 30%	1710
May	1st to 10th	Night	15% 6% 2 7% 5% 4 5% 5% 6% 8% 37%	2818
	11th to 20th	Night	12% 6% 3 7% 4 5% 4 4 6% 9% 41%	2495
	21st to end	Night	11% 7% 3 7% 4 4 4 4 6% 9% 40%	2738
June	1st to 10th	Night	14% 8% 3 7% 5% 4 4 5% 6% 8% 37%	1372
	11th to 20th	Night	12% 6% 1 5% 4 4 5% 3 7% 10% 43%	1330
	21st to end	Night	13% 6% 2 6% 4 4 5% 4 5% 8% 42%	1330
July	1st to 10th	Night	12% 6% 2 7% 4 4 4 3 5% 7% 45%	2210
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 5% 7% 48%	2227
	21st to end	Night	9% 6% 2 5% 4 4 4 3 6% 7% 51%	2983
August	1st to 10th	Night	11% 6% 3 6% 3 4 5% 3 5% 9% 45%	2825
	11th to 20th	Night	12% 6% 3 7% 4 4 4 4 5% 7% 44%	2785
	21st to end	Night	12% 5% 2 5% 4 3 3 3 5% 7% 51%	3151
September	1st to 10th	Night	13% 5% 2 5% 4 4 3 4 6% 8% 47%	1900
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 4 7% 49%	2056
	21st to end	Night	17% 7% 2 7% 4 3 4 4 5% 7% 40%	2096
October	1st to 10th	Night	20% 8% 3 7% 4 4 4 3 4 6% 36%	2280
	11th to 20th	Night	26% 10% 3 8% 6% 4 4 4 5% 5% 26%	2280
	21st to end	Night	27% 12% 4 8% 4 5% 4 3 4 6% 24%	2562
November	1st to 10th	Night	22% 13% 4 7% 3 3 3 3 5% 6% 29%	2585
	11th to 20th	Night	18% 17% 4 9% 5% 5% 5% 4 5% 6% 23%	2660
	21st to end	Night	25% 20% 5% 8% 5% 5% 4 4 4 4 16%	2660
December	1st to 10th	Night	20% 25% 5% 10% 6% 5% 4 3 4 4 14%	2660
	11th to 20th	Night	21% 21% 6% 9% 4 4 4 3 4 5% 19%	3411
	21st to end	Night	23% 21% 6% 13% 5% 5% 3 2 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	73% 8% 9% 9% 2	2209
	11th to 20th	Day	73% 6% 9% 9% 3 1	2452
	21st to end	Day	69% 8% 9% 9% 5% 1	3124
February	1st to 10th	Day	64% 6% 8% 17% 5%	1710
	11th to 20th	Day	56% 7% 12% 16% 8% 1	1672
	21st to end	Day	59% 6% 10% 18% 7%	1475
March	1st to 10th	Day	55% 7% 14% 13% 11% 1	3370
	11th to 20th	Day	52% 9% 13% 17% 7% 1	3480
	21st to end	Day	44% 9% 11% 22% 10% 2	3815
April	1st to 10th	Day	52% 7% 11% 18% 11% 1	2218
	11th to 20th	Day	47% 7% 7% 24% 14% 1	2423
	21st to end	Day	48% 6% 10% 19% 13% 3	2470
May	1st to 10th	Day	43% 8% 11% 24% 12% 1	4120
	11th to 20th	Day	36% 9% 15% 29% 10% 1	4402
	21st to end	Day	40% 8% 13% 19% 18% 3	4837
June	1st to 10th	Day	43% 7% 10% 25% 14% 1	2804
	11th to 20th	Day	38% 7% 12% 26% 17% 1	2850
	21st to end	Day	43% 9% 12% 24% 11% 1	2850
July	1st to 10th	Day	42% 8% 15% 23% 11% 1	4686
	11th to 20th	Day	31% 8% 17% 34% 10% 1	4660
	21st to end	Day	31% 7% 12% 28% 21% 1	4420
August	1st to 10th	Day	35% 8% 14% 30% 11%	4091
	11th to 20th	Day	38% 8% 16% 27% 11%	4083
	21st to end	Day	33% 7% 13% 35% 11%	4473
September	1st to 10th	Day	39% 8% 13% 28% 11% 1	2280
	11th to 20th	Day	35% 8% 15% 31% 11% 1	2122
	21st to end	Day	47% 8% 13% 23% 9%	2082
October	1st to 10th	Day	40% 7% 14% 27% 13%	3160
	11th to 20th	Day	47% 6% 17% 24% 6%	3140
	21st to end	Day	59% 7% 14% 15% 5%	3335
November	1st to 10th	Day	57% 7% 13% 18% 5%	1592
	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	74% 8% 7% 9% 3	4748
	11th to 20th	Night	70% 9% 10% 8% 3	4496
	21st to end	Night	71% 6% 8% 10% 5% 1	4532
February	1st to 10th	Night	62% 6% 11% 16% 5%	2470
	11th to 20th	Night	59% 5% 14% 15% 7% 1	2405
	21st to end	Night	60% 6% 12% 15% 7% 1	1979
March	1st to 10th	Night	48% 7% 14% 18% 13% 1	3483
	11th to 20th	Night	49% 8% 14% 18% 8% 2	3480
	21st to end	Night	46% 7% 11% 23% 11% 2	3817
April	1st to 10th	Night	55% 5% 8% 19% 11% 2	1961
	11th to 20th	Night	49% 5% 8% 21% 16% 2	1722
	21st to end	Night	54% 5% 10% 15% 15% 2	1710
May	1st to 10th	Night	41% 9% 11% 27% 11% 2	2825
	11th to 20th	Night	38% 6% 12% 25% 17% 2	2496
	21st to end	Night	39% 7% 12% 24% 15% 4	2739
June	1st to 10th	Night	43% 6% 12% 22% 15% 2	1372
	11th to 20th	Night	35% 6% 14% 24% 20% 1	1330
	21st to end	Night	39% 6% 15% 24% 13% 2	1330
July	1st to 10th	Night	37% 5% 15% 25% 15% 3	2175
	11th to 20th	Night	34% 6% 13% 36% 11% 1	2185
	21st to end	Night	32% 7% 10% 28% 22% 2	2888
August	1st to 10th	Night	36% 6% 17% 26% 14% 1	2814
	11th to 20th	Night	37% 7% 19% 25% 11% 1	2812
	21st to end	Night	32% 6% 13% 35% 13% 1	3151
September	1st to 10th	Night	34% 6% 16% 28% 13% 2	1900
	11th to 20th	Night	35% 6% 16% 31% 12%	2056
	21st to end	Night	43% 6% 15% 26% 10%	2096
October	1st to 10th	Night	39% 6% 10% 28% 16%	3800
	11th to 20th	Night	46% 7% 17% 25% 5%	3779
	21st to end	Night	53% 6% 18% 17% 6%	4210
November	1st to 10th	Night	55% 7% 13% 20% 6%	2585
	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	22% 19% 32% 21% 5% 1	231
	21st to end	Day	29% 13% 34% 17% 6% 1	297
February	1st to 10th	Day	28% 25% 32% 12% 3	270
	11th to 20th	Day	21% 19% 46% 12% 1	270
	21st to end	Day	33% 26% 32% 9%	225
March	1st to 10th	Day	22% 20% 36% 18% 4	417
	11th to 20th	Day	19% 20% 36% 18% 5% 1	460
	21st to end	Day	25% 18% 34% 19% 5% 1	506
April	1st to 10th	Day	23% 17% 34% 18% 8%	460
	11th to 20th	Day	29% 18% 26% 16% 8% 3	452
	21st to end	Day	26% 15% 32% 18% 7% 1	460
May	1st to 10th	Day	23% 8% 35% 25% 8% 2	463
	11th to 20th	Day	17% 13% 30% 24% 12% 3	487
	21st to end	Day	17% 11% 30% 28% 12% 2	529
June	1st to 10th	Day	17% 10% 32% 31% 9% 1	634
	11th to 20th	Day	13% 10% 35% 28% 11% 2	680
	21st to end	Day	18% 11% 30% 31% 8% 2	680
July	1st to 10th	Day	11% 6% 31% 35% 15% 2	671
	11th to 20th	Day	12% 7% 30% 33% 14% 4	662
	21st to end	Day	11% 5% 31% 34% 15% 4	532
August	1st to 10th	Day	14% 7% 26% 32% 15% 6%	486
	11th to 20th	Day	13% 7% 23% 32% 17% 9%	479
	21st to end	Day	16% 9% 27% 28% 15% 4	539
September	1st to 10th	Day	16% 11% 28% 26% 14% 5%	490
	11th to 20th	Day	14% 7% 26% 28% 19% 6%	490
	21st to end	Day	24% 8% 23% 26% 16% 3	490
October	1st to 10th	Day	22% 16% 28% 21% 12% 2	490
	11th to 20th	Day	28% 16% 33% 19% 4	490
	21st to end	Day	34% 18% 29% 17% 1 1	482
November	1st to 10th	Day	30% 18% 34% 15% 3	226
	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% 17% 30% 21% 5% 1	950
	11th to 20th	Night	28% 16% 30% 21% 5%	902
	21st to end	Night	22% 10% 33% 26% 8% 1	836
February	1st to 10th	Night	23% 18% 34% 20% 4	760
	11th to 20th	Night	21% 14% 34% 24% 6%	743
	21st to end	Night	23% 18% 31% 24% 4	628
March	1st to 10th	Night	18% 17% 35% 25% 5%	760
	11th to 20th	Night	21% 13% 35% 23% 6% 1	760
	21st to end	Night	18% 11% 34% 26% 9%	836
April	1st to 10th	Night	25% 12% 32% 24% 6%	760
	11th to 20th	Night	24% 11% 27% 26% 10% 1	598
	21st to end	Night	25% 10% 27% 24% 14%	570
May	1st to 10th	Night	19% 7% 25% 35% 13% 2	568
	11th to 20th	Night	16% 6% 28% 35% 14% 1	374
	21st to end	Night	12% 6% 31% 36% 15% 1	411
June	1st to 10th	Night	16% 5% 27% 38% 13% 1	380
	11th to 20th	Night	15% 9% 20% 37% 18% 1	380
	21st to end	Night	16% 5% 23% 34% 20% 2	380
July	1st to 10th	Night	9% 5% 18% 47% 19% 1	370
	11th to 20th	Night	13% 2 23% 36% 24% 2	368
	21st to end	Night	10% 7% 23% 35% 23% 2	559
August	1st to 10th	Night	13% 4 19% 38% 23% 4	567
	11th to 20th	Night	12% 5% 19% 33% 26% 4	564
	21st to end	Night	16% 7% 21% 30% 23% 2	641
September	1st to 10th	Night	15% 6% 27% 29% 20% 4	760
	11th to 20th	Night	14% 6% 24% 29% 21% 5%	760
	21st to end	Night	19% 7% 24% 30% 17% 3	760
October	1st to 10th	Night	24% 11% 28% 24% 12% 2	760
	11th to 20th	Night	31% 13% 26% 22% 8% 1	760
	21st to end	Night	32% 15% 30% 19% 4	836
November	1st to 10th	Night	32% 12% 27% 21% 8%	760
	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 2024-11-03 02:11:11. Version ac07

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