Stargate 4173 at Grimaldi Tower
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stargate 4173 at Grimaldi Tower clear sky chart from 2005-11-06 to 2025-09-19.

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% 8% 3 7% 4 4 4 4 5% 7% 38%	126255
	Night	16% 8% 3 7% 4 4 4 3 5% 6% 39%	122769
Transparency	Day	44% 4 11% 23% 14% 2	129769
	Night	44% 4 12% 22% 15% 3	127342
Seeing	Day	24% 17% 29% 20% 9% 2	16059
	Night	22% 15% 28% 26% 8% 1	25096

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	12% 9% 3 8% 5% 4 4 3 5% 5% 41%	3597
	11th to 20th	Day	14% 10% 3 8% 6% 4 4 3 5% 6% 37%	3570
	21st to end	Day	17% 10% 4 7% 4 4 4 3 5% 5% 37%	4172
February	1st to 10th	Day	17% 9% 2 8% 6% 4 4 4 5% 6% 34%	1811
	11th to 20th	Day	14% 8% 3 7% 5% 5% 4 4 5% 7% 37%	1948
	21st to end	Day	18% 9% 3 7% 4 4 4 3 4 6% 37%	1650
March	1st to 10th	Day	22% 8% 3 7% 4 3 4 2 4 4 38%	4476
	11th to 20th	Day	12% 8% 3 7% 4 4 4 4 5% 7% 42%	4699
	21st to end	Day	19% 7% 3 7% 5% 4 4 4 5% 6% 36%	5968
April	1st to 10th	Day	19% 9% 3 6% 5% 4 4 3 5% 6% 35%	2400
	11th to 20th	Day	17% 7% 3 8% 5% 5% 4 4 5% 7% 38%	2374
	21st to end	Day	20% 6% 2 5% 5% 4 4 4 4 6% 39%	2469
May	1st to 10th	Day	27% 10% 3 5% 4 4 4 4 5% 8% 27%	5886
	11th to 20th	Day	19% 9% 3 7% 4 4 4 3 5% 6% 35%	6290
	21st to end	Day	20% 7% 3 6% 4 4 4 4 6% 8% 34%	6949
June	1st to 10th	Day	17% 6% 2 6% 5% 5% 5% 4 7% 9% 35%	2800
	11th to 20th	Day	15% 7% 3 6% 5% 5% 5% 4 7% 9% 35%	2800
	21st to end	Day	12% 7% 3 7% 5% 5% 4 5% 6% 9% 38%	2800
July	1st to 10th	Day	10% 8% 3 8% 5% 5% 5% 5% 7% 8% 35%	6360
	11th to 20th	Day	10% 7% 2 7% 5% 5% 7% 5% 8% 10% 33%	6360
	21st to end	Day	13% 7% 3 6% 4 4 5% 4 5% 8% 41%	6926
August	1st to 10th	Day	19% 7% 3 7% 5% 5% 4 5% 6% 8% 32%	4401
	11th to 20th	Day	11% 7% 3 6% 4 4 5% 4 7% 9% 40%	3850
	21st to end	Day	10% 5% 2 6% 4 4 4 4 5% 10% 45%	4312
September	1st to 10th	Day	13% 6% 2 5% 5% 5% 4 4 5% 7% 43%	2400
	11th to 20th	Day	12% 4 2 6% 4 4 4 3 6% 7% 48%	2276
	21st to end	Day	18% 6% 2 6% 3 4 4 4 5% 7% 40%	2090
October	1st to 10th	Day	21% 7% 2 5% 4 3 4 3 5% 5% 41%	2005
	11th to 20th	Day	13% 7% 2 5% 4 4 4 4 5% 7% 45%	1900
	21st to end	Day	21% 7% 2 5% 5% 4 4 3 5% 7% 37%	1904
November	1st to 10th	Day	13% 7% 2 4 4 3 4 2 5% 7% 49%	1761
	11th to 20th	Day	17% 7% 2 5% 4 3 3 3 6% 6% 44%	1800
	21st to end	Day	18% 7% 2 5% 4 3 4 3 5% 7% 41%	1705
December	1st to 10th	Day	15% 9% 3 7% 4 3 4 3 4 7% 41%	2600
	11th to 20th	Day	20% 8% 2 6% 4 3 3 3 4 6% 41%	2986
	21st to end	Day	18% 11% 4 8% 4 4 3 3 4 7% 35%	3960
January	1st to 10th	Night	13% 6% 3 8% 5% 5% 5% 4 5% 6% 39%	6349
	11th to 20th	Night	12% 8% 3 9% 5% 4 4 4 5% 6% 38%	6315
	21st to end	Night	17% 9% 3 7% 5% 4 4 3 5% 6% 37%	6767
February	1st to 10th	Night	16% 10% 3 6% 4 5% 4 3 5% 6% 38%	2587
	11th to 20th	Night	15% 8% 3 7% 6% 4 5% 5% 5% 7% 36%	2338
	21st to end	Night	17% 8% 3 8% 5% 3 3 4 5% 6% 38%	1980
March	1st to 10th	Night	19% 9% 3 5% 3 3 3 3 5% 6% 39%	5364
	11th to 20th	Night	14% 9% 3 7% 5% 4 4 3 5% 6% 40%	5255
	21st to end	Night	18% 11% 3 7% 4 4 4 3 5% 5% 37%	4963
April	1st to 10th	Night	18% 9% 3 7% 6% 5% 5% 3 6% 7% 32%	2000
	11th to 20th	Night	19% 8% 2 7% 6% 4 3 3 5% 6% 37%	1975
	21st to end	Night	20% 8% 3 6% 4 3 4 3 5% 5% 40%	1930
May	1st to 10th	Night	31% 8% 3 7% 4 3 4 3 4 6% 26%	4054
	11th to 20th	Night	18% 10% 4 8% 5% 4 4 3 5% 6% 34%	3631
	21st to end	Night	21% 7% 3 6% 4 4 4 3 6% 7% 34%	3926
June	1st to 10th	Night	16% 6% 3 6% 5% 4 5% 3 5% 8% 40%	1600
	11th to 20th	Night	14% 7% 2 7% 4 5% 3 4 7% 8% 39%	1600
	21st to end	Night	13% 6% 2 5% 4 4 4 4 7% 10% 41%	1600
July	1st to 10th	Night	11% 8% 2 7% 5% 4 6% 4 7% 8% 38%	3600
	11th to 20th	Night	14% 8% 3 8% 5% 5% 5% 4 7% 9% 32%	3600
	21st to end	Night	12% 7% 3 6% 3 3 4 3 5% 6% 47%	3926
August	1st to 10th	Night	20% 8% 3 8% 5% 5% 5% 5% 5% 7% 31%	2700
	11th to 20th	Night	14% 7% 2 7% 4 5% 5% 3 6% 8% 40%	3197
	21st to end	Night	11% 5% 2 5% 3 3 3 3 5% 6% 53%	3586
September	1st to 10th	Night	15% 6% 2 6% 4 4 4 3 4 6% 47%	2000
	11th to 20th	Night	12% 6% 2 4 3 3 3 3 5% 7% 53%	2079
	21st to end	Night	17% 6% 2 6% 3 3 4 3 6% 7% 43%	2090
October	1st to 10th	Night	19% 7% 2 6% 4 3 4 2 4 6% 41%	2173
	11th to 20th	Night	14% 6% 2 6% 4 3 4 3 5% 6% 46%	2280
	21st to end	Night	20% 8% 2 6% 5% 4 4 3 5% 6% 38%	2693
November	1st to 10th	Night	13% 8% 2 5% 3 4 4 4 5% 6% 47%	2537
	11th to 20th	Night	18% 8% 2 5% 4 4 3 3 5% 6% 43%	2600
	21st to end	Night	14% 7% 3 6% 4 4 4 4 5% 7% 41%	2690
December	1st to 10th	Night	15% 10% 3 6% 4 4 4 3 5% 6% 41%	4580
	11th to 20th	Night	23% 9% 3 6% 4 3 4 3 4 4 37%	5208
	21st to end	Night	18% 12% 4 8% 4 4 3 3 5% 5% 35%	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	42% 4 8% 29% 14% 3	3598
	11th to 20th	Day	48% 3 9% 22% 12% 6%	3600
	21st to end	Day	49% 3 8% 23% 15% 1	4172
February	1st to 10th	Day	49% 4 12% 21% 13% 1	1811
	11th to 20th	Day	46% 4 9% 23% 15% 2	1957
	21st to end	Day	50% 2 10% 22% 13% 2	1650
March	1st to 10th	Day	50% 3 10% 17% 12% 9%	4479
	11th to 20th	Day	40% 4 13% 29% 9% 4	4699
	21st to end	Day	49% 4 7% 13% 22% 5%	5968
April	1st to 10th	Day	50% 4 8% 21% 14% 3	2400
	11th to 20th	Day	45% 4 10% 22% 16% 2	2374
	21st to end	Day	45% 4 10% 22% 17% 3	2469
May	1st to 10th	Day	57% 5% 14% 15% 9% 1	5897
	11th to 20th	Day	50% 4 11% 21% 12% 1	6294
	21st to end	Day	46% 5% 12% 23% 12% 1	6949
June	1st to 10th	Day	44% 6% 13% 23% 13% 1	2800
	11th to 20th	Day	45% 6% 13% 24% 11% 2	2800
	21st to end	Day	42% 7% 13% 25% 13% 1	2800
July	1st to 10th	Day	45% 8% 12% 21% 14% 1	6290
	11th to 20th	Day	43% 6% 16% 23% 11% 1	6285
	21st to end	Day	41% 5% 11% 23% 19% 1	6728
August	1st to 10th	Day	50% 6% 13% 22% 9% 1	4387
	11th to 20th	Day	38% 5% 17% 30% 10%	3886
	21st to end	Day	35% 4 12% 33% 15% 1	4312
September	1st to 10th	Day	39% 5% 10% 25% 18% 2	2400
	11th to 20th	Day	35% 4 9% 26% 24% 2	2276
	21st to end	Day	43% 5% 10% 22% 17% 3	2090
October	1st to 10th	Day	41% 4 8% 19% 25% 3	3330
	11th to 20th	Day	31% 4 9% 26% 26% 4	3140
	21st to end	Day	32% 3 16% 27% 20% 3	3116
November	1st to 10th	Day	36% 4 13% 27% 17% 3	1761
	11th to 20th	Day	40% 3 10% 24% 19% 3	1800
	21st to end	Day	43% 3 13% 29% 10% 2	1705
December	1st to 10th	Day	44% 3 16% 28% 9% 1	2600
	11th to 20th	Day	44% 3 15% 21% 15% 2	2986
	21st to end	Day	51% 3 8% 20% 14% 3	3960
January	1st to 10th	Night	42% 4 11% 24% 17% 2	6349
	11th to 20th	Night	45% 4 15% 19% 13% 5%	6360
	21st to end	Night	48% 3 10% 18% 17% 4	6767
February	1st to 10th	Night	48% 4 13% 23% 11% 2	2587
	11th to 20th	Night	46% 4 10% 19% 17% 4	2340
	21st to end	Night	46% 3 9% 23% 14% 4	1980
March	1st to 10th	Night	45% 4 12% 18% 15% 6%	5374
	11th to 20th	Night	44% 3 15% 24% 10% 4	5256
	21st to end	Night	49% 4 6% 14% 23% 5%	4963
April	1st to 10th	Night	50% 4 10% 20% 13% 3	2000
	11th to 20th	Night	48% 4 10% 19% 18% 1	1975
	21st to end	Night	46% 3 8% 22% 17% 3	1930
May	1st to 10th	Night	60% 4 13% 12% 10% 1	4060
	11th to 20th	Night	52% 5% 13% 17% 12% 2	3632
	21st to end	Night	48% 5% 13% 22% 10% 2	3927
June	1st to 10th	Night	44% 6% 10% 23% 16% 1	1600
	11th to 20th	Night	41% 6% 18% 25% 10% 1	1600
	21st to end	Night	37% 6% 16% 26% 15% 1	1600
July	1st to 10th	Night	42% 7% 14% 22% 14% 1	3560
	11th to 20th	Night	47% 6% 15% 20% 11% 1	3552
	21st to end	Night	37% 5% 12% 25% 19% 1	3809
August	1st to 10th	Night	52% 7% 14% 19% 9% 1	2690
	11th to 20th	Night	42% 5% 14% 29% 9%	3227
	21st to end	Night	32% 4 12% 36% 15% 1	3586
September	1st to 10th	Night	40% 4 10% 28% 18% 1	2000
	11th to 20th	Night	32% 4 11% 26% 26% 2	2079
	21st to end	Night	42% 5% 8% 22% 22% 1	2090
October	1st to 10th	Night	42% 5% 11% 22% 19% 1	3628
	11th to 20th	Night	29% 3 10% 29% 26% 4	3779
	21st to end	Night	35% 3 14% 29% 17% 2	4431
November	1st to 10th	Night	37% 4 12% 23% 21% 3	2537
	11th to 20th	Night	42% 4 9% 22% 20% 3	2600
	21st to end	Night	40% 4 14% 30% 10% 1	2690
December	1st to 10th	Night	43% 4 13% 32% 9% 1	4580
	11th to 20th	Night	50% 3 13% 18% 15% 2	5208
	21st to end	Night	51% 3 10% 17% 16% 4	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	33% 26% 24% 13% 4	200
	11th to 20th	Day	38% 24% 26% 11% 3	200
	21st to end	Day	27% 28% 32% 9% 3 1	267
February	1st to 10th	Day	34% 28% 29% 7% 2	311
	11th to 20th	Day	30% 28% 29% 12% 1	496
	21st to end	Day	33% 23% 29% 12% 3	414
March	1st to 10th	Day	30% 21% 33% 13% 3	500
	11th to 20th	Day	31% 22% 29% 14% 3 1	500
	21st to end	Day	32% 23% 30% 9% 4 2	550
April	1st to 10th	Day	36% 23% 23% 11% 6% 1	500
	11th to 20th	Day	27% 26% 28% 11% 7% 1	492
	21st to end	Day	30% 17% 34% 14% 4 2	500
May	1st to 10th	Day	36% 18% 26% 13% 5% 2	503
	11th to 20th	Day	24% 19% 31% 18% 6% 1	527
	21st to end	Day	21% 12% 29% 25% 10% 3	573
June	1st to 10th	Day	21% 11% 30% 24% 12% 1	530
	11th to 20th	Day	18% 14% 31% 22% 12% 2	530
	21st to end	Day	16% 14% 29% 26% 14% 2	530
July	1st to 10th	Day	15% 9% 30% 30% 13% 3	525
	11th to 20th	Day	13% 7% 29% 32% 17% 2	524
	21st to end	Day	14% 9% 33% 30% 13% 2	576
August	1st to 10th	Day	16% 8% 26% 29% 15% 5%	526
	11th to 20th	Day	16% 7% 27% 29% 16% 6%	519
	21st to end	Day	12% 10% 30% 28% 14% 7%	583
September	1st to 10th	Day	19% 12% 23% 23% 15% 7%	530
	11th to 20th	Day	13% 9% 27% 24% 16% 10%	522
	21st to end	Day	22% 12% 29% 21% 11% 5%	490
October	1st to 10th	Day	29% 11% 24% 18% 14% 4	490
	11th to 20th	Day	18% 20% 28% 22% 10% 2	490
	21st to end	Day	29% 12% 27% 21% 10% 1	441
November	1st to 10th	Day	20% 20% 25% 23% 10% 2	395
	11th to 20th	Day	29% 22% 26% 17% 6% 1	400
	21st to end	Day	28% 21% 28% 17% 5% 1	305
December	1st to 10th	Day	26% 27% 32% 12% 4 1	200
	11th to 20th	Day	34% 26% 27% 13% 1	200
	21st to end	Day	25% 26% 30% 14% 5%	220
January	1st to 10th	Night	22% 21% 35% 20% 2	800
	11th to 20th	Night	26% 21% 28% 22% 3	800
	21st to end	Night	20% 24% 33% 20% 3	880
February	1st to 10th	Night	25% 20% 32% 22% 1	800
	11th to 20th	Night	25% 22% 36% 16% 1	783
	21st to end	Night	26% 22% 32% 18% 3	660
March	1st to 10th	Night	25% 21% 32% 19% 3	800
	11th to 20th	Night	24% 23% 30% 19% 4	800
	21st to end	Night	25% 21% 33% 16% 5%	880
April	1st to 10th	Night	26% 22% 31% 18% 3	800
	11th to 20th	Night	25% 17% 31% 22% 5%	791
	21st to end	Night	25% 20% 30% 20% 5%	730
May	1st to 10th	Night	28% 15% 30% 21% 5% 1	600
	11th to 20th	Night	23% 13% 32% 26% 5%	424
	21st to end	Night	19% 7% 27% 36% 11%	433
June	1st to 10th	Night	18% 8% 29% 33% 12% 1	400
	11th to 20th	Night	18% 7% 28% 32% 14% 1	400
	21st to end	Night	16% 5% 23% 44% 13% 1	400
July	1st to 10th	Night	16% 5% 18% 39% 21% 1	390
	11th to 20th	Night	14% 5% 21% 43% 15% 2	388
	21st to end	Night	13% 4 24% 42% 17%	438
August	1st to 10th	Night	13% 3 25% 41% 17% 2	460
	11th to 20th	Night	15% 4 19% 40% 21% 2	790
	21st to end	Night	16% 5% 20% 36% 20% 2	880
September	1st to 10th	Night	18% 6% 26% 33% 15% 3	800
	11th to 20th	Night	15% 7% 22% 32% 20% 4	793
	21st to end	Night	22% 7% 25% 30% 14% 2	760
October	1st to 10th	Night	24% 11% 23% 27% 14% 2	760
	11th to 20th	Night	18% 13% 29% 28% 10% 1	760
	21st to end	Night	26% 13% 26% 28% 7%	836
November	1st to 10th	Night	18% 13% 31% 28% 10% 1	780
	11th to 20th	Night	23% 18% 29% 22% 7% 1	800
	21st to end	Night	21% 19% 29% 25% 6% 1	800
December	1st to 10th	Night	27% 17% 30% 21% 5%	800
	11th to 20th	Night	25% 19% 29% 23% 4	800
	21st to end	Night	26% 18% 31% 22% 2	880

Page generated at 2025-09-16 01:49:16. Version ac07

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