Lagoon City
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lagoon City clear sky chart from 2005-11-06 to 2025-10-04.

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	15% 10% 3 8% 5% 4 4 4 5% 7% 34%	127321
	Night	16% 12% 4 9% 5% 4 4 3 5% 6% 30%	122035
Transparency	Day	50% 5% 13% 21% 11% 1	130908
	Night	53% 4 12% 19% 10% 1	126536
Seeing	Day	18% 7% 24% 30% 16% 5%	15927
	Night	20% 7% 27% 31% 13% 2	24825

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% 15% 6% 12% 5% 5% 5% 3 5% 5% 26%	3597
	11th to 20th	Day	10% 18% 7% 17% 9% 8% 6% 4 4 5% 13%	3776
	21st to end	Day	13% 18% 7% 13% 6% 6% 5% 4 5% 5% 17%	4466
February	1st to 10th	Day	13% 17% 5% 14% 7% 6% 5% 5% 5% 5% 20%	1800
	11th to 20th	Day	11% 15% 7% 12% 6% 5% 4 4 4 7% 25%	1753
	21st to end	Day	16% 15% 4 11% 7% 6% 4 3 5% 6% 23%	1515
March	1st to 10th	Day	19% 11% 5% 10% 6% 4 4 3 5% 5% 30%	4932
	11th to 20th	Day	12% 12% 5% 10% 6% 6% 6% 4 6% 7% 28%	4980
	21st to end	Day	19% 11% 4 8% 4 4 4 3 4 5% 35%	5465
April	1st to 10th	Day	18% 11% 3 8% 6% 5% 4 3 5% 5% 31%	2380
	11th to 20th	Day	20% 9% 3 6% 5% 4 4 3 5% 5% 37%	2452
	21st to end	Day	19% 10% 3 7% 5% 4 4 3 4 6% 35%	2600
May	1st to 10th	Day	17% 7% 3 8% 5% 4 5% 3 5% 7% 35%	5973
	11th to 20th	Day	16% 9% 2 7% 4 4 4 3 5% 7% 39%	6318
	21st to end	Day	20% 8% 3 6% 5% 4 4 4 6% 7% 36%	6949
June	1st to 10th	Day	17% 7% 2 7% 4 4 4 4 5% 7% 38%	2800
	11th to 20th	Day	12% 6% 2 6% 5% 4 4 5% 7% 9% 40%	2866
	21st to end	Day	16% 6% 2 7% 4 5% 5% 3 6% 9% 38%	3000
July	1st to 10th	Day	12% 5% 2 7% 4 4 5% 4 6% 9% 41%	6645
	11th to 20th	Day	10% 5% 2 5% 4 4 4 3 5% 8% 49%	6360
	21st to end	Day	8% 4 2 5% 4 4 5% 4 7% 9% 48%	6635
August	1st to 10th	Day	14% 6% 3 6% 4 4 5% 4 5% 8% 41%	4234
	11th to 20th	Day	13% 6% 3 6% 4 5% 4 4 7% 11% 37%	4174
	21st to end	Day	9% 5% 2 6% 5% 4 4 4 6% 9% 45%	4492
September	1st to 10th	Day	13% 6% 2 6% 5% 5% 4 3 5% 8% 42%	2400
	11th to 20th	Day	11% 6% 1 5% 4 4 4 3 5% 7% 49%	2305
	21st to end	Day	16% 7% 2 8% 5% 5% 5% 4 5% 6% 38%	2145
October	1st to 10th	Day	20% 8% 2 7% 4 5% 5% 4 4 7% 35%	1930
	11th to 20th	Day	23% 10% 3 9% 5% 4 5% 4 5% 6% 26%	1900
	21st to end	Day	25% 11% 4 9% 5% 5% 5% 4 5% 5% 23%	2090
November	1st to 10th	Day	17% 12% 4 7% 5% 5% 5% 4 5% 6% 29%	1643
	11th to 20th	Day	17% 12% 4 11% 5% 5% 6% 4 7% 7% 23%	1600
	21st to end	Day	19% 19% 5% 9% 6% 5% 5% 4 6% 6% 17%	1600
December	1st to 10th	Day	18% 24% 6% 12% 7% 5% 4 3 5% 5% 12%	2600
	11th to 20th	Day	19% 20% 5% 11% 5% 4 4 3 4 6% 20%	2986
	21st to end	Day	25% 16% 5% 13% 5% 4 4 3 4 4 17%	3960
January	1st to 10th	Night	14% 18% 8% 14% 6% 5% 4 3 4 5% 19%	6349
	11th to 20th	Night	12% 14% 8% 17% 9% 6% 5% 3 5% 5% 14%	6105
	21st to end	Night	14% 17% 7% 13% 5% 5% 4 3 5% 5% 22%	6490
February	1st to 10th	Night	12% 17% 5% 13% 8% 6% 6% 4 5% 6% 19%	2600
	11th to 20th	Night	13% 14% 6% 10% 6% 5% 5% 4 5% 6% 26%	2533
	21st to end	Night	14% 15% 4 11% 6% 5% 4 3 6% 6% 26%	2108
March	1st to 10th	Night	17% 12% 4 10% 5% 4 5% 3 5% 6% 30%	4908
	11th to 20th	Night	10% 11% 5% 9% 5% 5% 6% 5% 7% 7% 31%	4979
	21st to end	Night	20% 9% 4 7% 4 4 4 4 5% 6% 33%	5467
April	1st to 10th	Night	20% 11% 3 9% 5% 4 5% 4 5% 5% 30%	2020
	11th to 20th	Night	17% 9% 3 7% 5% 4 3 4 6% 7% 36%	1912
	21st to end	Night	16% 9% 3 10% 5% 4 4 4 5% 6% 34%	1800
May	1st to 10th	Night	20% 8% 3 7% 4 4 4 3 5% 7% 34%	3966
	11th to 20th	Night	13% 6% 2 6% 4 5% 5% 3 6% 7% 42%	3575
	21st to end	Night	18% 7% 2 6% 4 4 4 3 4 7% 40%	3926
June	1st to 10th	Night	15% 7% 2 6% 6% 4 5% 4 6% 8% 39%	1600
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 7% 9% 43%	1526
	21st to end	Night	14% 7% 3 6% 5% 5% 5% 4 6% 6% 40%	1400
July	1st to 10th	Night	11% 5% 2 6% 5% 4 5% 4 5% 8% 44%	3309
	11th to 20th	Night	14% 6% 2 4 3 3 4 3 5% 7% 50%	3600
	21st to end	Night	10% 4 2 5% 3 4 4 3 6% 8% 50%	4213
August	1st to 10th	Night	10% 5% 2 6% 4 5% 4 4 6% 7% 47%	2915
	11th to 20th	Night	13% 6% 2 5% 3 4 4 3 5% 7% 47%	2875
	21st to end	Night	13% 5% 2 6% 4 4 5% 3 5% 8% 47%	3373
September	1st to 10th	Night	11% 5% 2 6% 4 5% 5% 4 6% 8% 45%	2000
	11th to 20th	Night	11% 5% 1 4 5% 3 4 3 6% 7% 51%	2090
	21st to end	Night	17% 8% 3 6% 4 4 4 3 5% 6% 41%	2255
October	1st to 10th	Night	18% 6% 3 6% 5% 5% 4 4 6% 6% 35%	2317
	11th to 20th	Night	21% 10% 4 8% 5% 5% 5% 3 5% 5% 28%	2280
	21st to end	Night	21% 14% 3 8% 6% 4 5% 3 5% 6% 25%	2508
November	1st to 10th	Night	19% 11% 3 7% 4 4 4 3 5% 7% 32%	2652
	11th to 20th	Night	17% 17% 4 8% 6% 5% 4 4 5% 6% 25%	2800
	21st to end	Night	21% 16% 4 10% 6% 5% 5% 4 5% 6% 17%	2800
December	1st to 10th	Night	19% 22% 6% 12% 5% 5% 4 4 5% 5% 13%	4580
	11th to 20th	Night	16% 21% 7% 15% 7% 5% 4 3 4 4 14%	5208
	21st to end	Night	23% 19% 6% 15% 6% 4 4 3 4 4 14%	6996

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	61% 3 11% 15% 9%	3598
	11th to 20th	Day	74% 5% 8% 9% 4	3808
	21st to end	Day	67% 5% 10% 9% 8%	4466
February	1st to 10th	Day	64% 4 11% 16% 4 1	1800
	11th to 20th	Day	59% 5% 11% 16% 8% 1	1762
	21st to end	Day	63% 4 10% 16% 7%	1515
March	1st to 10th	Day	55% 4 14% 12% 14%	4935
	11th to 20th	Day	53% 3 15% 20% 7% 2	4980
	21st to end	Day	51% 4 9% 20% 15% 1	5465
April	1st to 10th	Day	53% 5% 9% 20% 11% 1	2380
	11th to 20th	Day	49% 4 10% 23% 15% 1	2452
	21st to end	Day	51% 5% 10% 19% 13% 3	2600
May	1st to 10th	Day	47% 4 13% 21% 10% 5%	5982
	11th to 20th	Day	45% 5% 12% 18% 18% 1	6322
	21st to end	Day	48% 4 12% 21% 13% 3	6949
June	1st to 10th	Day	45% 6% 12% 23% 14% 1	2800
	11th to 20th	Day	38% 6% 14% 26% 14% 1	2866
	21st to end	Day	41% 7% 16% 24% 12% 1	3000
July	1st to 10th	Day	39% 4 16% 27% 13% 1	6575
	11th to 20th	Day	34% 3 13% 33% 15% 1	6285
	21st to end	Day	32% 5% 14% 34% 14%	6445
August	1st to 10th	Day	42% 4 15% 26% 11% 1	4221
	11th to 20th	Day	40% 5% 18% 27% 10%	4213
	21st to end	Day	35% 4 14% 35% 11% 1	4492
September	1st to 10th	Day	40% 5% 14% 29% 10% 1	2400
	11th to 20th	Day	34% 5% 14% 33% 12%	2305
	21st to end	Day	46% 6% 13% 25% 9%	2145
October	1st to 10th	Day	44% 4 12% 28% 11% 1	3190
	11th to 20th	Day	48% 3 16% 23% 9%	3140
	21st to end	Day	55% 5% 15% 19% 6%	3428
November	1st to 10th	Day	55% 6% 14% 17% 7%	1643
	11th to 20th	Day	59% 8% 12% 14% 6% 1	1600
	21st to end	Day	67% 7% 12% 12% 2	1600
December	1st to 10th	Day	75% 4 12% 7% 2	2600
	11th to 20th	Day	68% 6% 9% 13% 5%	2986
	21st to end	Day	72% 5% 7% 9% 7%	3960
January	1st to 10th	Night	68% 3 8% 14% 7%	6349
	11th to 20th	Night	70% 4 10% 10% 5%	6148
	21st to end	Night	65% 4 11% 10% 9% 1	6490
February	1st to 10th	Night	65% 5% 10% 15% 4 1	2600
	11th to 20th	Night	59% 5% 12% 17% 8%	2535
	21st to end	Night	58% 4 12% 18% 7%	2108
March	1st to 10th	Night	56% 3 10% 16% 12% 3	4918
	11th to 20th	Night	50% 3 19% 19% 8% 1	4980
	21st to end	Night	51% 5% 9% 20% 14% 1	5467
April	1st to 10th	Night	56% 4 9% 19% 11% 1	2020
	11th to 20th	Night	47% 4 9% 22% 16% 2	1912
	21st to end	Night	51% 6% 11% 15% 16% 1	1800
May	1st to 10th	Night	49% 3 12% 16% 15% 5%	3973
	11th to 20th	Night	41% 5% 13% 23% 17% 2	3576
	21st to end	Night	45% 3 13% 25% 13% 1	3927
June	1st to 10th	Night	42% 6% 11% 23% 16% 2	1600
	11th to 20th	Night	36% 6% 13% 24% 20% 1	1526
	21st to end	Night	43% 6% 13% 23% 14% 1	1400
July	1st to 10th	Night	39% 3 15% 26% 16% 1	3271
	11th to 20th	Night	35% 3 13% 31% 18%	3552
	21st to end	Night	33% 4 10% 36% 16% 1	4088
August	1st to 10th	Night	37% 4 15% 26% 16% 1	2904
	11th to 20th	Night	37% 4 17% 27% 14% 1	2902
	21st to end	Night	37% 4 12% 34% 12% 1	3373
September	1st to 10th	Night	35% 7% 16% 29% 12% 1	2000
	11th to 20th	Night	33% 5% 13% 33% 15%	2090
	21st to end	Night	44% 5% 13% 27% 11%	2255
October	1st to 10th	Night	38% 5% 10% 28% 18% 1	3837
	11th to 20th	Night	49% 4 15% 24% 9%	3779
	21st to end	Night	50% 5% 14% 23% 7%	4120
November	1st to 10th	Night	52% 6% 13% 21% 8%	2652
	11th to 20th	Night	59% 7% 12% 14% 6% 1	2800
	21st to end	Night	66% 8% 13% 10% 2	2800
December	1st to 10th	Night	74% 4 13% 7% 2	4580
	11th to 20th	Night	74% 5% 9% 10% 3	5208
	21st to end	Night	77% 3 7% 8% 5%	6996

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	18% 13% 37% 21% 10% 2	200
	11th to 20th	Day	19% 11% 37% 25% 8% 1	246
	21st to end	Day	24% 8% 29% 29% 8% 1	330
February	1st to 10th	Day	22% 14% 32% 26% 6% 1	300
	11th to 20th	Day	18% 12% 36% 30% 4	300
	21st to end	Day	26% 12% 29% 30% 2	269
March	1st to 10th	Day	20% 6% 33% 33% 7%	500
	11th to 20th	Day	17% 12% 32% 30% 9% 1	500
	21st to end	Day	27% 5% 27% 29% 11% 1	550
April	1st to 10th	Day	21% 7% 29% 32% 8% 2	500
	11th to 20th	Day	26% 6% 27% 26% 12% 4	492
	21st to end	Day	22% 9% 24% 31% 11% 3	500
May	1st to 10th	Day	20% 5% 22% 32% 16% 5%	503
	11th to 20th	Day	16% 3 20% 35% 20% 6%	527
	21st to end	Day	17% 2 20% 31% 22% 8%	573
June	1st to 10th	Day	18% 4 19% 36% 20% 3	530
	11th to 20th	Day	13% 4 23% 34% 20% 7%	596
	21st to end	Day	17% 5% 22% 35% 18% 4	730
July	1st to 10th	Day	9% 3 16% 39% 26% 7%	654
	11th to 20th	Day	13% 3 16% 32% 28% 8%	524
	21st to end	Day	8% 2 19% 37% 26% 8%	576
August	1st to 10th	Day	10% 4 14% 33% 30% 10%	526
	11th to 20th	Day	12% 3 15% 27% 32% 11%	519
	21st to end	Day	13% 5% 16% 29% 28% 9%	583
September	1st to 10th	Day	12% 7% 18% 29% 23% 12%	530
	11th to 20th	Day	10% 3 13% 29% 28% 18%	530
	21st to end	Day	18% 5% 21% 29% 20% 7%	530
October	1st to 10th	Day	21% 5% 25% 25% 15% 9%	502
	11th to 20th	Day	22% 13% 27% 27% 8% 2	490
	21st to end	Day	29% 11% 27% 24% 8% 1	539
November	1st to 10th	Day	23% 15% 26% 26% 9% 1	258
	11th to 20th	Day	20% 14% 37% 22% 7% 2	200
	21st to end	Day	25% 15% 31% 27% 3	200
December	1st to 10th	Day	23% 16% 30% 27% 3 1	200
	11th to 20th	Day	28% 21% 29% 19% 3 2	200
	21st to end	Day	28% 12% 33% 21% 5%	220
January	1st to 10th	Night	23% 12% 37% 21% 7% 2	800
	11th to 20th	Night	26% 9% 30% 27% 7% 1	800
	21st to end	Night	20% 8% 27% 34% 9% 1	880
February	1st to 10th	Night	21% 7% 35% 32% 6%	800
	11th to 20th	Night	19% 9% 33% 31% 7% 1	783
	21st to end	Night	21% 7% 34% 32% 5%	660
March	1st to 10th	Night	21% 6% 32% 36% 6%	800
	11th to 20th	Night	17% 7% 36% 33% 7% 1	800
	21st to end	Night	21% 5% 27% 34% 12%	880
April	1st to 10th	Night	25% 5% 27% 35% 8%	800
	11th to 20th	Night	20% 5% 28% 33% 12% 2	728
	21st to end	Night	20% 5% 27% 35% 13% 1	600
May	1st to 10th	Night	22% 3 17% 39% 17% 2	565
	11th to 20th	Night	14% 6% 22% 38% 18% 2	394
	21st to end	Night	14% 3 18% 40% 23% 2	433
June	1st to 10th	Night	16% 4 23% 39% 17% 2	400
	11th to 20th	Night	11% 4 22% 42% 20% 2	400
	21st to end	Night	16% 5% 16% 39% 22% 2	400
July	1st to 10th	Night	8% 2 17% 45% 25% 3	390
	11th to 20th	Night	11% 4 19% 39% 25% 3	388
	21st to end	Night	12% 1 15% 44% 26% 1	559
August	1st to 10th	Night	10% 2 16% 38% 31% 4	597
	11th to 20th	Night	9% 2 18% 37% 30% 5%	594
	21st to end	Night	13% 3 19% 35% 28% 3	745
September	1st to 10th	Night	12% 5% 20% 34% 23% 6%	800
	11th to 20th	Night	14% 2 16% 33% 27% 9%	800
	21st to end	Night	21% 5% 18% 30% 19% 7%	800
October	1st to 10th	Night	20% 6% 28% 27% 16% 3	773
	11th to 20th	Night	24% 10% 29% 25% 10% 2	760
	21st to end	Night	28% 12% 29% 26% 5%	836
November	1st to 10th	Night	24% 11% 27% 27% 11% 1	780
	11th to 20th	Night	24% 13% 34% 21% 7% 1	800
	21st to end	Night	27% 15% 31% 22% 5%	800
December	1st to 10th	Night	30% 15% 32% 19% 4	800
	11th to 20th	Night	23% 15% 36% 20% 5% 1	800
	21st to end	Night	30% 9% 34% 23% 4	880

Page generated at 2025-10-01 01:39:03. Version ac07

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