Keoma Public Fields
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Keoma Public Fields clear sky chart from 2005-11-06 to 2025-07-21.

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	8% 9% 3 8% 5% 5% 5% 4 6% 8% 38%	124042
	Night	6% 9% 4 9% 6% 5% 5% 4 6% 8% 36%	123797
Transparency	Day	41% 7% 15% 24% 11% 2	123786
	Night	43% 7% 15% 22% 11% 2	123696
Seeing	Day	13% 9% 27% 29% 17% 5%	16308
	Night	11% 6% 31% 35% 14% 2	25351

By Month

Percentage Cloud Cover NW (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	3 10% 6% 16% 8% 6% 5% 4 5% 7% 30%	3179
	11th to 20th	Day	3 9% 4 11% 6% 5% 6% 5% 7% 7% 36%	3178
	21st to end	Day	4 6% 4 9% 5% 5% 5% 4 6% 9% 44%	4004
February	1st to 10th	Day	5% 13% 5% 13% 7% 5% 6% 5% 7% 8% 27%	1600
	11th to 20th	Day	6% 11% 4 11% 7% 5% 6% 6% 7% 8% 28%	1755
	21st to end	Day	3 13% 5% 11% 7% 6% 5% 5% 6% 8% 31%	1589
March	1st to 10th	Day	2 10% 4 11% 6% 5% 4 4 7% 10% 37%	4518
	11th to 20th	Day	5% 10% 4 9% 5% 4 4 4 7% 9% 39%	4971
	21st to end	Day	8% 20% 6% 14% 6% 5% 5% 4 6% 6% 21%	5529
April	1st to 10th	Day	7% 14% 4 10% 6% 5% 7% 5% 7% 7% 29%	2470
	11th to 20th	Day	11% 13% 4 9% 5% 5% 6% 4 6% 8% 29%	2570
	21st to end	Day	11% 12% 4 9% 5% 6% 5% 5% 5% 8% 31%	2600
May	1st to 10th	Day	14% 10% 3 6% 4 5% 5% 4 5% 7% 38%	6227
	11th to 20th	Day	12% 11% 4 9% 6% 6% 6% 5% 8% 8% 25%	6734
	21st to end	Day	12% 7% 2 8% 5% 5% 6% 4 6% 7% 37%	7405
June	1st to 10th	Day	15% 7% 3 7% 6% 6% 6% 5% 7% 9% 30%	3000
	11th to 20th	Day	17% 9% 3 7% 5% 6% 6% 5% 7% 8% 27%	3000
	21st to end	Day	8% 5% 2 6% 6% 5% 6% 4 8% 10% 40%	3000
July	1st to 10th	Day	7% 4 2 6% 4 4 5% 5% 7% 9% 48%	4890
	11th to 20th	Day	7% 3 1 4 3 4 4 4 8% 11% 50%	4890
	21st to end	Day	4 3 1 4 4 4 4 4 6% 9% 57%	5060
August	1st to 10th	Day	8% 6% 2 6% 5% 5% 5% 5% 7% 9% 42%	4401
	11th to 20th	Day	6% 5% 2 5% 5% 5% 5% 5% 7% 11% 44%	4058
	21st to end	Day	10% 4 1 4 3 4 4 3 5% 8% 53%	4521
September	1st to 10th	Day	10% 6% 2 6% 4 4 3 3 6% 7% 50%	2365
	11th to 20th	Day	15% 8% 2 5% 3 4 4 3 5% 6% 44%	2090
	21st to end	Day	7% 9% 3 6% 4 4 5% 4 5% 8% 44%	2090
October	1st to 10th	Day	7% 6% 3 7% 5% 5% 5% 4 7% 8% 42%	3332
	11th to 20th	Day	6% 7% 2 7% 4 5% 5% 4 6% 9% 44%	2936
	21st to end	Day	7% 7% 3 7% 5% 5% 5% 4 5% 7% 44%	3101
November	1st to 10th	Day	9% 16% 5% 8% 6% 5% 4 4 5% 7% 31%	1616
	11th to 20th	Day	7% 11% 4 8% 6% 5% 5% 4 6% 7% 37%	1533
	21st to end	Day	5% 14% 4 9% 6% 5% 4 4 8% 10% 32%	1400
December	1st to 10th	Day	5% 12% 5% 12% 5% 5% 7% 4 6% 7% 32%	2290
	11th to 20th	Day	5% 11% 4 13% 8% 6% 5% 5% 6% 7% 30%	2642
	21st to end	Day	3 9% 4 9% 5% 5% 5% 4 6% 8% 42%	3498
January	1st to 10th	Night	3 13% 6% 15% 8% 7% 6% 4 6% 7% 25%	6766
	11th to 20th	Night	2 10% 4 13% 6% 6% 7% 5% 6% 8% 34%	6739
	21st to end	Night	3 10% 5% 9% 5% 5% 4 4 6% 8% 41%	6975
February	1st to 10th	Night	4 10% 5% 13% 7% 7% 7% 4 6% 7% 29%	2800
	11th to 20th	Night	5% 13% 5% 11% 7% 5% 6% 6% 6% 8% 28%	2532
	21st to end	Night	3 11% 5% 11% 7% 7% 5% 5% 7% 9% 32%	2040
March	1st to 10th	Night	3 8% 4 12% 7% 7% 6% 4 7% 10% 33%	5376
	11th to 20th	Night	5% 8% 4 10% 5% 6% 5% 5% 7% 8% 36%	5027
	21st to end	Night	8% 19% 6% 13% 7% 5% 6% 4 5% 7% 20%	5432
April	1st to 10th	Night	8% 12% 3 9% 6% 6% 5% 4 8% 9% 28%	1930
	11th to 20th	Night	9% 12% 4 10% 6% 7% 5% 4 6% 7% 30%	1781
	21st to end	Night	11% 11% 4 7% 6% 6% 5% 4 7% 8% 32%	1800
May	1st to 10th	Night	13% 11% 3 8% 5% 4 4 4 5% 6% 37%	3742
	11th to 20th	Night	12% 10% 4 9% 6% 5% 5% 4 8% 10% 29%	3159
	21st to end	Night	11% 8% 2 9% 5% 5% 5% 5% 7% 6% 36%	3470
June	1st to 10th	Night	15% 9% 4 7% 6% 5% 5% 4 6% 8% 32%	1400
	11th to 20th	Night	16% 8% 3 9% 5% 6% 4 5% 7% 8% 29%	1400
	21st to end	Night	9% 5% 3 5% 5% 5% 7% 5% 8% 8% 42%	1400
July	1st to 10th	Night	6% 5% 2 6% 6% 5% 6% 5% 7% 8% 46%	2290
	11th to 20th	Night	5% 3 2 5% 4 4 6% 6% 10% 12% 44%	2290
	21st to end	Night	4 4 2 4 4 4 4 4 6% 9% 55%	2492
August	1st to 10th	Night	10% 6% 2 6% 4 4 5% 4 7% 9% 42%	2529
	11th to 20th	Night	6% 5% 2 6% 4 4 6% 5% 8% 12% 41%	2778
	21st to end	Night	8% 4 1 5% 3 4 4 4 6% 9% 51%	3146
September	1st to 10th	Night	9% 6% 2 7% 3 4 4 4 6% 7% 49%	1813
	11th to 20th	Night	13% 7% 2 5% 4 4 4 3 5% 8% 46%	2090
	21st to end	Night	9% 7% 2 5% 3 4 4 4 6% 9% 47%	2090
October	1st to 10th	Night	7% 6% 2 6% 4 4 4 4 6% 8% 48%	3642
	11th to 20th	Night	6% 8% 2 5% 4 5% 5% 4 6% 8% 46%	3988
	21st to end	Night	5% 7% 3 7% 5% 4 6% 4 7% 8% 43%	4457
November	1st to 10th	Night	9% 13% 4 9% 5% 5% 5% 4 5% 7% 34%	2660
	11th to 20th	Night	4 12% 4 9% 6% 5% 5% 4 7% 8% 35%	2865
	21st to end	Night	4 12% 3 9% 7% 6% 5% 4 6% 8% 35%	3000
December	1st to 10th	Night	5% 12% 5% 11% 7% 6% 6% 5% 7% 8% 30%	4890
	11th to 20th	Night	4 10% 6% 14% 7% 6% 6% 5% 6% 9% 27%	5550
	21st to end	Night	3 10% 4 9% 5% 5% 5% 4 6% 7% 42%	7458

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	52% 7% 11% 20% 9% 1	3179
	11th to 20th	Day	45% 6% 13% 16% 17% 3	3199
	21st to end	Day	36% 7% 16% 29% 12% 1	4004
February	1st to 10th	Day	53% 7% 15% 14% 9% 2	1600
	11th to 20th	Day	51% 9% 13% 18% 9% 1	1764
	21st to end	Day	49% 6% 13% 21% 10% 1	1589
March	1st to 10th	Day	41% 6% 15% 22% 15%	4518
	11th to 20th	Day	39% 6% 16% 23% 15% 1	4972
	21st to end	Day	61% 7% 13% 14% 5%	5529
April	1st to 10th	Day	50% 9% 16% 17% 8%	2470
	11th to 20th	Day	49% 8% 13% 20% 9% 1	2570
	21st to end	Day	50% 8% 14% 19% 9% 1	2600
May	1st to 10th	Day	45% 6% 10% 22% 13% 4	6227
	11th to 20th	Day	49% 9% 15% 21% 6%	6738
	21st to end	Day	42% 9% 15% 24% 9% 1	7406
June	1st to 10th	Day	45% 9% 16% 19% 9% 1	3000
	11th to 20th	Day	50% 9% 15% 18% 6% 2	3000
	21st to end	Day	36% 9% 21% 25% 8% 2	3000
July	1st to 10th	Day	29% 8% 18% 28% 15% 3	4816
	11th to 20th	Day	26% 8% 20% 35% 10% 1	4809
	21st to end	Day	21% 6% 16% 29% 21% 6%	4900
August	1st to 10th	Day	36% 8% 17% 31% 8% 1	4384
	11th to 20th	Day	31% 8% 25% 29% 6% 1	4097
	21st to end	Day	29% 6% 20% 32% 12% 1	4520
September	1st to 10th	Day	33% 6% 17% 25% 14% 5%	2365
	11th to 20th	Day	39% 6% 14% 27% 11% 2	2090
	21st to end	Day	36% 8% 15% 26% 12% 3	2090
October	1st to 10th	Day	38% 6% 19% 30% 7% 1	3332
	11th to 20th	Day	35% 6% 21% 25% 12% 2	2936
	21st to end	Day	39% 6% 10% 32% 12% 1	3101
November	1st to 10th	Day	52% 7% 10% 20% 8% 2	1616
	11th to 20th	Day	45% 7% 15% 22% 9% 1	1533
	21st to end	Day	44% 9% 16% 22% 7% 2	1400
December	1st to 10th	Day	50% 6% 13% 22% 7% 2	2290
	11th to 20th	Day	51% 7% 17% 18% 5% 1	2644
	21st to end	Day	37% 7% 12% 23% 18% 3	3498
January	1st to 10th	Night	56% 7% 11% 19% 5% 2	6766
	11th to 20th	Night	47% 6% 12% 17% 14% 3	6780
	21st to end	Night	40% 6% 15% 26% 13% 1	6975
February	1st to 10th	Night	50% 7% 13% 17% 11% 2	2800
	11th to 20th	Night	50% 7% 12% 18% 10% 2	2533
	21st to end	Night	45% 8% 13% 20% 13% 2	2040
March	1st to 10th	Night	42% 8% 17% 20% 10% 1	5376
	11th to 20th	Night	40% 8% 16% 22% 12% 1	5027
	21st to end	Night	61% 7% 11% 12% 7% 1	5432
April	1st to 10th	Night	48% 8% 14% 18% 12%	1930
	11th to 20th	Night	50% 7% 14% 20% 8% 1	1781
	21st to end	Night	47% 8% 14% 21% 9% 2	1800
May	1st to 10th	Night	47% 6% 9% 21% 14% 3	3739
	11th to 20th	Night	45% 10% 15% 23% 7%	3159
	21st to end	Night	42% 11% 17% 23% 7% 1	3470
June	1st to 10th	Night	49% 8% 14% 19% 10% 1	1400
	11th to 20th	Night	49% 11% 14% 17% 7% 2	1400
	21st to end	Night	35% 11% 20% 25% 8% 1	1400
July	1st to 10th	Night	33% 8% 17% 23% 18% 1	2255
	11th to 20th	Night	27% 9% 20% 33% 7% 3	2248
	21st to end	Night	23% 7% 13% 31% 21% 5%	2413
August	1st to 10th	Night	35% 7% 16% 30% 11% 1	2521
	11th to 20th	Night	32% 10% 24% 27% 7% 1	2805
	21st to end	Night	29% 5% 21% 32% 11% 2	3146
September	1st to 10th	Night	33% 8% 16% 23% 14% 6%	1813
	11th to 20th	Night	37% 6% 15% 24% 13% 4	2090
	21st to end	Night	33% 7% 17% 26% 14% 4	2090
October	1st to 10th	Night	33% 5% 18% 27% 16% 2	3642
	11th to 20th	Night	34% 7% 18% 25% 15% 2	3988
	21st to end	Night	37% 6% 12% 32% 13%	4457
November	1st to 10th	Night	48% 7% 12% 20% 10% 2	2660
	11th to 20th	Night	44% 8% 16% 19% 12% 1	2865
	21st to end	Night	44% 9% 17% 19% 9% 2	3000
December	1st to 10th	Night	50% 7% 17% 18% 6% 2	4890
	11th to 20th	Night	52% 8% 19% 16% 5%	5547
	21st to end	Night	39% 5% 10% 25% 16% 3	7458

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	6% 10% 30% 31% 15% 10%	200
	11th to 20th	Day	9% 10% 37% 26% 15% 5%	200
	21st to end	Day	8% 10% 34% 32% 13% 3	220
February	1st to 10th	Day	13% 12% 35% 28% 10% 4	200
	11th to 20th	Day	9% 9% 35% 31% 14% 1	300
	21st to end	Day	8% 10% 37% 29% 13% 3	353
March	1st to 10th	Day	9% 12% 35% 29% 11% 4	500
	11th to 20th	Day	8% 13% 34% 30% 11% 3	500
	21st to end	Day	16% 14% 33% 21% 13% 3	550
April	1st to 10th	Day	13% 14% 33% 26% 12% 2	500
	11th to 20th	Day	14% 14% 27% 28% 12% 3	492
	21st to end	Day	17% 12% 29% 25% 14% 3	500
May	1st to 10th	Day	18% 10% 23% 27% 16% 4	568
	11th to 20th	Day	16% 7% 23% 30% 20% 5%	725
	21st to end	Day	15% 7% 21% 30% 21% 6%	789
June	1st to 10th	Day	15% 9% 25% 34% 14% 4	730
	11th to 20th	Day	19% 8% 27% 26% 17% 2	730
	21st to end	Day	10% 5% 22% 34% 22% 7%	730
July	1st to 10th	Day	11% 4 20% 34% 25% 6%	721
	11th to 20th	Day	12% 3 23% 31% 24% 6%	718
	21st to end	Day	5% 4 22% 35% 25% 8%	697
August	1st to 10th	Day	10% 7% 22% 30% 24% 7%	487
	11th to 20th	Day	9% 3 20% 34% 25% 8%	477
	21st to end	Day	9% 9% 20% 29% 22% 9%	539
September	1st to 10th	Day	14% 8% 26% 29% 18% 6%	490
	11th to 20th	Day	20% 6% 23% 28% 19% 5%	490
	21st to end	Day	13% 14% 26% 29% 12% 5%	490
October	1st to 10th	Day	18% 9% 24% 28% 15% 6%	397
	11th to 20th	Day	11% 9% 33% 28% 14% 5%	300
	21st to end	Day	14% 16% 29% 28% 11% 2	330
November	1st to 10th	Day	17% 12% 31% 26% 12% 3	300
	11th to 20th	Day	15% 11% 35% 29% 6% 3	265
	21st to end	Day	8% 11% 36% 25% 14% 7%	200
December	1st to 10th	Day	9% 7% 42% 26% 13% 4	200
	11th to 20th	Day	10% 9% 40% 27% 13% 2	200
	21st to end	Day	8% 6% 28% 32% 20% 6%	220
January	1st to 10th	Night	9% 8% 35% 34% 13% 2	1000
	11th to 20th	Night	9% 8% 39% 32% 11% 1	1000
	21st to end	Night	10% 9% 37% 31% 11% 1	890
February	1st to 10th	Night	8% 10% 31% 33% 15% 4	800
	11th to 20th	Night	9% 7% 32% 38% 13% 1	784
	21st to end	Night	7% 7% 33% 32% 18% 5%	660
March	1st to 10th	Night	8% 6% 33% 34% 16% 3	800
	11th to 20th	Night	8% 6% 36% 35% 13% 2	800
	21st to end	Night	13% 7% 31% 33% 14% 2	880
April	1st to 10th	Night	11% 7% 33% 34% 14% 2	730
	11th to 20th	Night	14% 7% 36% 32% 11%	593
	21st to end	Night	14% 8% 31% 35% 11% 1	600
May	1st to 10th	Night	15% 8% 30% 33% 14%	515
	11th to 20th	Night	13% 6% 27% 36% 16% 1	394
	21st to end	Night	19% 5% 22% 33% 19% 1	433
June	1st to 10th	Night	17% 10% 26% 32% 13% 2	400
	11th to 20th	Night	18% 4 30% 35% 13% 1	400
	21st to end	Night	11% 4 21% 41% 21% 2	400
July	1st to 10th	Night	10% 4 17% 42% 27% 2	390
	11th to 20th	Night	11% 2 23% 42% 19% 2	388
	21st to end	Night	4 2 20% 45% 26% 3	416
August	1st to 10th	Night	11% 3 17% 40% 27% 1	378
	11th to 20th	Night	9% 3 17% 46% 24% 1	543
	21st to end	Night	11% 5% 22% 38% 24% 1	627
September	1st to 10th	Night	11% 3 26% 38% 19% 2	649
	11th to 20th	Night	14% 5% 21% 37% 21% 2	760
	21st to end	Night	12% 4 31% 36% 15% 2	760
October	1st to 10th	Night	15% 6% 26% 36% 16% 3	760
	11th to 20th	Night	13% 5% 32% 35% 14% 2	760
	21st to end	Night	11% 8% 34% 35% 11%	836
November	1st to 10th	Night	14% 10% 35% 30% 10% 1	905
	11th to 20th	Night	10% 8% 43% 31% 8% 2	1000
	21st to end	Night	9% 7% 38% 34% 10% 2	1000
December	1st to 10th	Night	10% 8% 34% 34% 12% 2	1000
	11th to 20th	Night	7% 6% 38% 37% 10% 1	1000
	21st to end	Night	12% 6% 32% 37% 11% 3	1100

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