Curiosity Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Curiosity Observatory clear sky chart from 2005-11-06 to 2026-03-18.

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% 12% 4 9% 5% 4 4 3 5% 6% 30%	131284
	Night	15% 14% 5% 10% 6% 5% 4 3 4 5% 28%	130306
Transparency	Day	54% 5% 11% 20% 8% 1	134815
	Night	57% 5% 10% 18% 9% 1	134863
Seeing	Day	23% 15% 31% 21% 8% 2	16783
	Night	24% 13% 31% 24% 8% 1	25961

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% 20% 9% 15% 8% 6% 4 3 3 5% 16%	4094
	11th to 20th	Day	10% 21% 8% 17% 6% 6% 4 3 4 6% 15%	4234
	21st to end	Day	9% 16% 8% 16% 9% 6% 4 4 4 5% 19%	5780
February	1st to 10th	Day	10% 20% 7% 13% 9% 6% 5% 3 5% 4 19%	1890
	11th to 20th	Day	11% 20% 6% 12% 8% 4 4 3 4 6% 23%	1843
	21st to end	Day	14% 17% 6% 14% 7% 6% 4 3 4 4 22%	1562
March	1st to 10th	Day	19% 16% 5% 10% 4 4 4 3 4 6% 24%	4992
	11th to 20th	Day	15% 13% 5% 14% 6% 5% 4 4 5% 6% 22%	5057
	21st to end	Day	14% 16% 6% 11% 5% 5% 4 3 4 4 29%	5465
April	1st to 10th	Day	20% 15% 4 9% 4 4 4 3 5% 6% 27%	2375
	11th to 20th	Day	22% 12% 3 8% 4 4 3 3 4 5% 32%	2530
	21st to end	Day	22% 12% 3 7% 4 4 3 3 4 4 34%	2600
May	1st to 10th	Day	20% 10% 3 7% 4 4 4 3 5% 6% 34%	6106
	11th to 20th	Day	14% 8% 3 7% 4 5% 4 3 5% 7% 39%	6318
	21st to end	Day	22% 9% 3 7% 4 3 3 3 4 7% 35%	6949
June	1st to 10th	Day	19% 10% 3 7% 5% 4 5% 4 5% 6% 32%	2980
	11th to 20th	Day	14% 6% 3 7% 5% 5% 5% 4 6% 8% 36%	3000
	21st to end	Day	19% 8% 3 7% 5% 5% 5% 5% 7% 7% 30%	3000
July	1st to 10th	Day	17% 8% 2 7% 5% 5% 5% 4 7% 9% 32%	6819
	11th to 20th	Day	14% 5% 2 6% 4 4 4 4 6% 9% 42%	6820
	21st to end	Day	12% 5% 2 6% 4 4 4 4 6% 9% 45%	6831
August	1st to 10th	Day	13% 7% 3 7% 5% 5% 5% 4 6% 9% 36%	4234
	11th to 20th	Day	19% 7% 2 6% 4 4 4 4 6% 8% 36%	4174
	21st to end	Day	12% 6% 2 7% 5% 5% 4 4 5% 8% 42%	4585
September	1st to 10th	Day	18% 8% 3 7% 4 5% 4 4 5% 7% 37%	2400
	11th to 20th	Day	17% 8% 2 4 4 4 4 3 5% 8% 40%	2290
	21st to end	Day	23% 9% 3 6% 5% 3 4 4 5% 6% 34%	2158
October	1st to 10th	Day	18% 11% 3 8% 5% 4 3 3 5% 6% 33%	2000
	11th to 20th	Day	24% 16% 3 9% 5% 5% 4 3 4 5% 24%	2000
	21st to end	Day	28% 17% 4 8% 4 3 4 3 4 5% 19%	2150
November	1st to 10th	Day	20% 16% 5% 9% 4 4 4 3 4 6% 25%	1649
	11th to 20th	Day	19% 18% 5% 13% 6% 4 4 3 4 5% 19%	1680
	21st to end	Day	24% 23% 5% 11% 5% 4 4 2 3 4 15%	1680
December	1st to 10th	Day	15% 23% 9% 16% 7% 4 4 2 4 4 11%	2680
	11th to 20th	Day	16% 20% 6% 13% 6% 4 3 2 3 4 23%	2806
	21st to end	Day	20% 20% 10% 17% 6% 3 2 2 4 4 12%	3553
January	1st to 10th	Night	10% 17% 9% 17% 10% 6% 5% 3 4 5% 14%	8831
	11th to 20th	Night	10% 20% 8% 16% 7% 6% 5% 3 3 4 17%	8672
	21st to end	Night	7% 17% 8% 16% 7% 8% 5% 4 5% 6% 18%	8401
February	1st to 10th	Night	10% 16% 6% 12% 9% 7% 5% 4 6% 5% 22%	2730
	11th to 20th	Night	12% 17% 7% 13% 8% 5% 4 3 4 4 22%	2663
	21st to end	Night	13% 18% 6% 10% 8% 6% 5% 3 5% 5% 22%	2240
March	1st to 10th	Night	15% 17% 4 9% 5% 4 5% 3 4 6% 27%	5068
	11th to 20th	Night	14% 17% 5% 11% 6% 5% 4 4 6% 6% 23%	5057
	21st to end	Night	17% 13% 6% 9% 6% 4 4 2 4 5% 30%	5467
April	1st to 10th	Night	20% 15% 4 8% 5% 3 3 3 4 5% 28%	2025
	11th to 20th	Night	19% 11% 4 6% 6% 4 3 3 4 5% 34%	1837
	21st to end	Night	22% 10% 3 7% 4 4 5% 4 4 7% 31%	1800
May	1st to 10th	Night	17% 11% 4 7% 4 4 4 3 5% 6% 36%	3833
	11th to 20th	Night	13% 7% 2 6% 4 5% 5% 4 5% 7% 43%	3575
	21st to end	Night	17% 10% 3 6% 5% 4 4 3 5% 7% 37%	3926
June	1st to 10th	Night	14% 10% 4 6% 6% 5% 4 4 5% 6% 36%	1416
	11th to 20th	Night	16% 7% 3 5% 5% 4 3 3 4 8% 43%	1400
	21st to end	Night	15% 8% 3 7% 5% 5% 4 4 6% 8% 35%	1400
July	1st to 10th	Night	17% 8% 3 8% 4 5% 4 4 5% 7% 36%	3160
	11th to 20th	Night	15% 7% 2 6% 4 4 4 3 5% 7% 45%	3160
	21st to end	Night	13% 6% 2 5% 3 3 3 3 5% 8% 49%	4005
August	1st to 10th	Night	12% 6% 2 6% 5% 5% 5% 4 6% 7% 42%	2915
	11th to 20th	Night	14% 8% 3 8% 4 4 4 3 5% 6% 42%	2875
	21st to end	Night	16% 5% 2 6% 4 3 3 3 5% 7% 46%	3279
September	1st to 10th	Night	16% 6% 2 5% 4 3 4 4 5% 7% 45%	2000
	11th to 20th	Night	15% 8% 2 6% 3 3 3 3 5% 5% 49%	2108
	21st to end	Night	19% 9% 2 6% 4 3 3 3 5% 6% 41%	2241
October	1st to 10th	Night	19% 9% 3 7% 4 4 5% 4 5% 5% 36%	2400
	11th to 20th	Night	26% 13% 2 8% 4 4 4 3 5% 4 27%	2400
	21st to end	Night	25% 15% 5% 8% 4 4 4 2 4 5% 24%	2688
November	1st to 10th	Night	20% 12% 4 8% 5% 5% 4 3 4 6% 29%	2867
	11th to 20th	Night	18% 17% 6% 11% 6% 5% 4 3 4 5% 22%	2940
	21st to end	Night	22% 20% 5% 10% 6% 4 3 3 4 4 17%	2940
December	1st to 10th	Night	15% 23% 7% 14% 8% 5% 4 3 4 4 12%	4720
	11th to 20th	Night	16% 21% 5% 13% 6% 5% 4 3 4 5% 19%	5600
	21st to end	Night	20% 21% 8% 15% 6% 4 4 2 3 3 14%	7667

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% 4 7% 11% 3 1	4095
	11th to 20th	Day	72% 4 6% 9% 9%	4261
	21st to end	Day	68% 4 6% 13% 9%	5780
February	1st to 10th	Day	68% 4 9% 12% 6% 1	1890
	11th to 20th	Day	63% 5% 10% 12% 9% 1	1852
	21st to end	Day	65% 5% 6% 15% 9% 1	1562
March	1st to 10th	Day	61% 6% 8% 11% 12% 2	4995
	11th to 20th	Day	60% 6% 11% 13% 8% 1	5057
	21st to end	Day	58% 4 9% 17% 10% 2	5465
April	1st to 10th	Day	57% 5% 10% 18% 8% 2	2375
	11th to 20th	Day	53% 5% 7% 22% 11% 1	2530
	21st to end	Day	54% 5% 8% 17% 13% 3	2600
May	1st to 10th	Day	50% 5% 9% 20% 12% 4	6115
	11th to 20th	Day	43% 7% 13% 23% 13% 2	6322
	21st to end	Day	50% 5% 10% 20% 13% 1	6949
June	1st to 10th	Day	50% 7% 11% 21% 11% 1	2980
	11th to 20th	Day	43% 8% 12% 24% 12% 1	3000
	21st to end	Day	51% 9% 12% 18% 9% 1	3000
July	1st to 10th	Day	47% 5% 17% 25% 6%	6746
	11th to 20th	Day	39% 5% 19% 33% 5%	6739
	21st to end	Day	36% 5% 18% 31% 10%	6635
August	1st to 10th	Day	44% 6% 13% 30% 6%	4221
	11th to 20th	Day	45% 6% 15% 25% 8%	4213
	21st to end	Day	40% 6% 13% 32% 9% 1	4585
September	1st to 10th	Day	46% 7% 14% 23% 10% 1	2400
	11th to 20th	Day	42% 7% 13% 28% 10%	2290
	21st to end	Day	51% 6% 12% 23% 7%	2158
October	1st to 10th	Day	50% 5% 12% 26% 7%	3260
	11th to 20th	Day	54% 6% 12% 19% 8%	3240
	21st to end	Day	68% 4 14% 9% 4	3452
November	1st to 10th	Day	60% 6% 12% 16% 6%	1649
	11th to 20th	Day	66% 7% 10% 11% 5% 1	1680
	21st to end	Day	74% 6% 8% 8% 4	1680
December	1st to 10th	Day	78% 4 8% 7% 2	2680
	11th to 20th	Day	67% 4 7% 17% 5%	2806
	21st to end	Day	77% 3 4 12% 4	3553
January	1st to 10th	Night	71% 6% 7% 11% 4	8831
	11th to 20th	Night	72% 5% 7% 9% 7%	8720
	21st to end	Night	67% 4 6% 12% 10% 1	8401
February	1st to 10th	Night	63% 6% 9% 15% 7% 1	2730
	11th to 20th	Night	65% 5% 9% 15% 6% 1	2665
	21st to end	Night	63% 6% 7% 15% 7% 1	2240
March	1st to 10th	Night	57% 6% 8% 13% 12% 4	5078
	11th to 20th	Night	60% 6% 12% 14% 7% 1	5058
	21st to end	Night	57% 5% 7% 18% 12% 3	5467
April	1st to 10th	Night	59% 4 9% 17% 11% 2	2025
	11th to 20th	Night	52% 5% 7% 21% 14% 2	1837
	21st to end	Night	53% 6% 10% 14% 15% 3	1800
May	1st to 10th	Night	48% 5% 7% 20% 16% 3	3840
	11th to 20th	Night	38% 7% 14% 21% 17% 3	3576
	21st to end	Night	46% 6% 11% 21% 14% 2	3927
June	1st to 10th	Night	48% 7% 10% 22% 11% 3	1416
	11th to 20th	Night	41% 6% 11% 23% 17% 1	1400
	21st to end	Night	46% 8% 13% 20% 12% 1	1400
July	1st to 10th	Night	46% 5% 12% 28% 8% 1	3125
	11th to 20th	Night	41% 4 15% 31% 9% 1	3118
	21st to end	Night	34% 4 14% 34% 14%	3887
August	1st to 10th	Night	40% 6% 14% 29% 10%	2904
	11th to 20th	Night	43% 6% 16% 27% 8% 1	2902
	21st to end	Night	37% 5% 15% 30% 11% 1	3279
September	1st to 10th	Night	38% 6% 16% 28% 10% 2	2000
	11th to 20th	Night	38% 6% 14% 32% 10% 1	2108
	21st to end	Night	43% 5% 16% 26% 10%	2241
October	1st to 10th	Night	47% 5% 11% 27% 10%	3920
	11th to 20th	Night	53% 4 13% 24% 5%	3899
	21st to end	Night	59% 5% 19% 12% 5%	4336
November	1st to 10th	Night	55% 7% 14% 18% 5%	2867
	11th to 20th	Night	63% 7% 10% 13% 6% 1	2940
	21st to end	Night	70% 7% 10% 10% 3	2940
December	1st to 10th	Night	76% 4 8% 9% 2	4720
	11th to 20th	Night	68% 5% 7% 11% 9%	5599
	21st to end	Night	76% 3 5% 12% 4	7667

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% 18% 37% 15% 4 1	220
	11th to 20th	Day	20% 15% 42% 16% 6% 1	231
	21st to end	Day	22% 15% 36% 19% 7% 1	363
February	1st to 10th	Day	28% 27% 31% 10% 4	330
	11th to 20th	Day	23% 23% 40% 13% 1	330
	21st to end	Day	32% 22% 35% 10% 1	273
March	1st to 10th	Day	25% 20% 36% 15% 3	514
	11th to 20th	Day	23% 21% 36% 17% 3 1	528
	21st to end	Day	24% 22% 33% 17% 3 1	550
April	1st to 10th	Day	27% 19% 30% 18% 5% 1	500
	11th to 20th	Day	32% 18% 24% 16% 7% 3	492
	21st to end	Day	32% 18% 28% 15% 5% 1	500
May	1st to 10th	Day	26% 13% 32% 18% 10% 1	503
	11th to 20th	Day	23% 15% 30% 21% 10% 2	527
	21st to end	Day	24% 13% 31% 22% 10% 1	573
June	1st to 10th	Day	21% 15% 36% 21% 7% 1	710
	11th to 20th	Day	16% 16% 34% 24% 8% 2	730
	21st to end	Day	22% 12% 31% 25% 8% 2	730
July	1st to 10th	Day	14% 11% 34% 30% 9% 1	721
	11th to 20th	Day	16% 11% 29% 28% 13% 3	718
	21st to end	Day	16% 10% 29% 31% 11% 4	586
August	1st to 10th	Day	18% 10% 25% 30% 13% 4	526
	11th to 20th	Day	19% 6% 23% 29% 14% 8%	519
	21st to end	Day	20% 10% 28% 23% 14% 4	583
September	1st to 10th	Day	20% 12% 31% 23% 11% 3	530
	11th to 20th	Day	17% 7% 28% 31% 10% 7%	530
	21st to end	Day	26% 9% 25% 25% 12% 3	530
October	1st to 10th	Day	24% 17% 28% 19% 11% 2	530
	11th to 20th	Day	29% 19% 34% 13% 3 1	530
	21st to end	Day	34% 17% 33% 15% 1 1	533
November	1st to 10th	Day	33% 20% 34% 11% 1	221
	11th to 20th	Day	25% 19% 40% 12% 3	220
	21st to end	Day	35% 20% 32% 10% 2	220
December	1st to 10th	Day	24% 23% 32% 20% 1	220
	11th to 20th	Day	30% 20% 30% 15% 4	220
	21st to end	Day	31% 20% 31% 13% 4 1	242
January	1st to 10th	Night	25% 13% 37% 20% 5%	1050
	11th to 20th	Night	27% 15% 31% 22% 4	1015
	21st to end	Night	19% 12% 35% 24% 9% 1	924
February	1st to 10th	Night	17% 18% 39% 22% 4	840
	11th to 20th	Night	21% 16% 39% 19% 5%	823
	21st to end	Night	23% 18% 33% 22% 4	692
March	1st to 10th	Night	20% 20% 36% 20% 5%	840
	11th to 20th	Night	24% 18% 35% 18% 5% 1	829
	21st to end	Night	20% 16% 35% 24% 5% 1	880
April	1st to 10th	Night	27% 15% 31% 22% 5%	800
	11th to 20th	Night	25% 17% 29% 20% 8% 1	653
	21st to end	Night	25% 14% 29% 23% 8% 1	600
May	1st to 10th	Night	22% 9% 32% 29% 8% 1	510
	11th to 20th	Night	18% 10% 32% 30% 8% 1	394
	21st to end	Night	20% 9% 33% 31% 7%	433
June	1st to 10th	Night	18% 9% 35% 30% 9%	400
	11th to 20th	Night	20% 7% 30% 32% 11% 1	400
	21st to end	Night	19% 9% 28% 29% 15% 1	400
July	1st to 10th	Night	13% 5% 33% 39% 11% 1	390
	11th to 20th	Night	13% 6% 30% 35% 16%	388
	21st to end	Night	11% 4 29% 39% 15% 1	478
August	1st to 10th	Night	16% 4 25% 37% 16% 2	597
	11th to 20th	Night	16% 4 24% 32% 22% 2	594
	21st to end	Night	19% 7% 27% 29% 15% 3	690
September	1st to 10th	Night	21% 6% 26% 28% 17% 1	800
	11th to 20th	Night	19% 8% 26% 28% 18% 3	800
	21st to end	Night	24% 7% 24% 28% 15% 2	800
October	1st to 10th	Night	23% 13% 26% 29% 7% 1	800
	11th to 20th	Night	34% 12% 28% 19% 6% 1	800
	21st to end	Night	34% 14% 26% 22% 4	880
November	1st to 10th	Night	28% 13% 32% 21% 5% 1	820
	11th to 20th	Night	27% 17% 31% 18% 6%	840
	21st to end	Night	34% 13% 31% 17% 5%	840
December	1st to 10th	Night	30% 17% 31% 16% 5% 1	840
	11th to 20th	Night	29% 15% 34% 17% 4 1	966
	21st to end	Night	31% 16% 30% 19% 4	1155

Page generated at 2026-03-15 02:23:56. Version ac07

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