Casa Becca del Norte Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Casa Becca del Norte Observatory clear sky chart from 2005-11-06 to 2024-11-10.

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	10% 9% 3 7% 5% 4 4 4 5% 7% 42%	105260
	Night	12% 10% 3 7% 5% 4 4 4 5% 7% 40%	102457
Transparency	Day	41% 6% 12% 21% 14% 6%	105028
	Night	44% 6% 12% 20% 13% 5%	102335
Seeing	Day	17% 11% 26% 27% 14% 4	14855
	Night	19% 4 15% 36% 22% 3	23931

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	18% 22% 7% 12% 6% 5% 5% 4 4 5% 13%	2539
	11th to 20th	Day	19% 14% 4 9% 7% 5% 5% 3 4 5% 24%	2516
	21st to end	Day	28% 22% 5% 9% 5% 3 3 3 4 5% 13%	2794
February	1st to 10th	Day	15% 16% 4 11% 7% 5% 4 4 6% 6% 23%	1520
	11th to 20th	Day	14% 15% 4 9% 4 5% 6% 4 7% 6% 27%	1750
	21st to end	Day	16% 15% 4 8% 5% 5% 5% 3 6% 5% 28%	1570
March	1st to 10th	Day	11% 17% 4 8% 6% 5% 5% 3 5% 7% 28%	3138
	11th to 20th	Day	11% 10% 3 6% 3 3 4 2 4 6% 48%	3255
	21st to end	Day	14% 15% 4 10% 7% 6% 6% 5% 6% 6% 21%	4158
April	1st to 10th	Day	14% 11% 5% 10% 7% 6% 6% 4 6% 7% 24%	2280
	11th to 20th	Day	11% 10% 3 9% 6% 5% 6% 5% 6% 7% 32%	2314
	21st to end	Day	11% 10% 4 8% 7% 5% 6% 4 5% 8% 32%	2470
May	1st to 10th	Day	8% 8% 3 7% 5% 5% 5% 5% 7% 9% 36%	4406
	11th to 20th	Day	6% 6% 3 7% 5% 5% 6% 5% 7% 11% 38%	4377
	21st to end	Day	11% 8% 4 9% 6% 7% 7% 6% 8% 8% 26%	4877
June	1st to 10th	Day	18% 8% 3 6% 5% 4 4 4 5% 6% 37%	2850
	11th to 20th	Day	12% 8% 3 9% 7% 6% 5% 4 6% 7% 33%	2850
	21st to end	Day	7% 5% 2 5% 4 5% 5% 4 5% 8% 51%	2850
July	1st to 10th	Day	2 2 1 3 3 2 3 3 5% 6% 70%	4517
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 77%	4420
	21st to end	Day	2 1 1 2 2 3 3 3 4 6% 73%	4790
August	1st to 10th	Day	3 3 1 3 2 3 4 3 5% 6% 67%	4401
	11th to 20th	Day	2 3 1 4 3 3 3 3 5% 8% 64%	4190
	21st to end	Day	4 3 2 4 3 4 5% 3 5% 7% 60%	4255
September	1st to 10th	Day	4 3 1 4 3 2 3 3 5% 5% 66%	2280
	11th to 20th	Day	7% 5% 2 5% 5% 5% 4 4 7% 8% 49%	2189
	21st to end	Day	9% 6% 2 6% 4 4 4 4 6% 7% 49%	2090
October	1st to 10th	Day	7% 5% 2 5% 4 3 3 3 5% 8% 54%	3318
	11th to 20th	Day	10% 6% 2 5% 5% 5% 5% 5% 7% 8% 43%	2976
	21st to end	Day	16% 8% 2 5% 3 4 5% 4 5% 7% 41%	3101
November	1st to 10th	Day	22% 14% 4 7% 3 4 4 3 6% 6% 27%	1755
	11th to 20th	Day	21% 14% 4 8% 5% 4 5% 3 3 5% 27%	1574
	21st to end	Day	16% 20% 5% 9% 5% 6% 3 3 5% 5% 22%	1368
December	1st to 10th	Day	17% 15% 5% 10% 5% 4 5% 4 4 6% 25%	1330
	11th to 20th	Day	22% 23% 6% 10% 6% 3 3 3 3 4 16%	1682
	21st to end	Day	16% 22% 7% 9% 5% 5% 5% 4 5% 6% 16%	2510
January	1st to 10th	Night	23% 21% 6% 10% 5% 4 4 3 3 4 16%	4406
	11th to 20th	Night	17% 16% 3 10% 6% 4 4 3 5% 6% 24%	4382
	21st to end	Night	25% 24% 6% 8% 4 4 4 3 3 4 15%	4862
February	1st to 10th	Night	16% 17% 4 8% 5% 4 4 3 4 6% 28%	2660
	11th to 20th	Night	13% 13% 4 9% 5% 5% 4 4 5% 6% 32%	2313
	21st to end	Night	11% 12% 4 7% 6% 6% 5% 4 5% 7% 33%	1884
March	1st to 10th	Night	8% 11% 3 7% 5% 5% 5% 4 6% 8% 37%	3736
	11th to 20th	Night	11% 9% 1 5% 4 3 3 3 4 5% 51%	3723
	21st to end	Night	13% 12% 3 9% 6% 6% 6% 5% 7% 7% 26%	3493
April	1st to 10th	Night	10% 9% 4 8% 6% 5% 6% 5% 6% 8% 33%	1900
	11th to 20th	Night	10% 8% 3 7% 6% 5% 5% 2 5% 7% 40%	1816
	21st to end	Night	8% 10% 3 7% 5% 4 5% 5% 7% 7% 39%	1710
May	1st to 10th	Night	9% 7% 2 6% 5% 5% 7% 4 8% 7% 38%	2550
	11th to 20th	Night	5% 5% 2 5% 4 5% 5% 4 7% 10% 48%	2516
	21st to end	Night	11% 7% 3 9% 6% 5% 6% 5% 6% 9% 32%	2680
June	1st to 10th	Night	11% 7% 2 6% 5% 5% 4 4 7% 9% 41%	1330
	11th to 20th	Night	9% 6% 2 7% 5% 6% 5% 6% 8% 8% 38%	1330
	21st to end	Night	6% 3 1 5% 4 3 5% 5% 5% 7% 57%	1330
July	1st to 10th	Night	2 2 3 2 2 3 3 4 6% 74%	2438
	11th to 20th	Night	1 1 1 2 2 2 2 2 3 4 81%	2540
	21st to end	Night	1 1 1 2 2 1 2 2 3 6% 79%	2762
August	1st to 10th	Night	3 2 1 3 2 2 3 2 4 7% 70%	2529
	11th to 20th	Night	2 2 1 4 3 3 4 4 5% 9% 63%	2641
	21st to end	Night	3 3 1 4 4 4 4 4 5% 7% 61%	3420
September	1st to 10th	Night	3 2 1 4 2 4 4 3 5% 7% 65%	1900
	11th to 20th	Night	6% 4 2 5% 4 4 5% 4 5% 9% 52%	1990
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 7% 53%	2090
October	1st to 10th	Night	6% 4 2 4 3 3 3 3 5% 8% 59%	3659
	11th to 20th	Night	10% 5% 2 5% 3 3 4 5% 6% 9% 48%	3954
	21st to end	Night	15% 7% 2 5% 4 4 5% 4 5% 7% 43%	4457
November	1st to 10th	Night	20% 12% 3 7% 5% 5% 5% 4 6% 7% 27%	2528
	11th to 20th	Night	20% 13% 4 8% 5% 4 4 4 5% 5% 28%	2603
	21st to end	Night	19% 14% 5% 11% 6% 4 4 3 4 5% 27%	2791
December	1st to 10th	Night	17% 15% 4 10% 6% 5% 4 3 4 6% 26%	2850
	11th to 20th	Night	21% 21% 7% 11% 6% 3 4 3 4 5% 15%	3510
	21st to end	Night	20% 18% 6% 11% 7% 5% 5% 4 5% 5% 16%	5174

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	72% 8% 8% 9% 3	2539
	11th to 20th	Day	61% 6% 12% 14% 3 3	2540
	21st to end	Day	75% 6% 10% 7% 2	2794
February	1st to 10th	Day	60% 9% 14% 11% 5% 2	1520
	11th to 20th	Day	56% 7% 14% 14% 7% 1	1759
	21st to end	Day	56% 7% 12% 14% 9% 1	1570
March	1st to 10th	Day	53% 8% 10% 16% 12% 1	3138
	11th to 20th	Day	38% 5% 20% 31% 6%	3255
	21st to end	Day	57% 12% 13% 12% 6% 1	4158
April	1st to 10th	Day	58% 6% 14% 16% 5% 1	2280
	11th to 20th	Day	49% 6% 14% 17% 11% 2	2314
	21st to end	Day	49% 6% 13% 20% 9% 3	2470
May	1st to 10th	Day	41% 6% 11% 28% 13% 1	4406
	11th to 20th	Day	34% 9% 13% 29% 13% 2	4380
	21st to end	Day	47% 11% 15% 20% 7%	4878
June	1st to 10th	Day	46% 6% 9% 21% 15% 3	2850
	11th to 20th	Day	49% 6% 11% 20% 12% 2	2850
	21st to end	Day	31% 6% 12% 27% 20% 4	2850
July	1st to 10th	Day	16% 4 6% 18% 30% 26%	4448
	11th to 20th	Day	13% 2 5% 12% 27% 40%	4345
	21st to end	Day	14% 3 6% 21% 34% 22%	4639
August	1st to 10th	Day	18% 4 7% 28% 30% 13%	4384
	11th to 20th	Day	18% 4 10% 42% 22% 4	4232
	21st to end	Day	24% 5% 12% 32% 24% 3	4254
September	1st to 10th	Day	21% 4 10% 32% 24% 9%	2280
	11th to 20th	Day	31% 6% 13% 25% 22% 4	2189
	21st to end	Day	33% 6% 18% 27% 12% 3	2090
October	1st to 10th	Day	30% 7% 15% 36% 12%	3318
	11th to 20th	Day	38% 9% 15% 22% 16%	2976
	21st to end	Day	43% 8% 16% 20% 12% 1	3101
November	1st to 10th	Day	58% 8% 13% 15% 4 1	1755
	11th to 20th	Day	61% 8% 12% 14% 4 2	1574
	21st to end	Day	64% 7% 12% 14% 4	1368
December	1st to 10th	Day	62% 7% 12% 14% 6%	1330
	11th to 20th	Day	75% 5% 12% 6% 3	1684
	21st to end	Day	67% 7% 14% 9% 3	2510
January	1st to 10th	Night	73% 7% 7% 10% 3	4406
	11th to 20th	Night	59% 6% 13% 15% 6% 2	4420
	21st to end	Night	73% 7% 11% 7% 2 1	4862
February	1st to 10th	Night	59% 6% 14% 14% 6% 1	2660
	11th to 20th	Night	52% 7% 15% 16% 9% 1	2315
	21st to end	Night	50% 6% 14% 16% 12% 1	1884
March	1st to 10th	Night	42% 7% 15% 23% 12% 1	3736
	11th to 20th	Night	36% 4 19% 32% 8%	3724
	21st to end	Night	52% 10% 14% 18% 6%	3493
April	1st to 10th	Night	47% 5% 15% 23% 9% 1	1900
	11th to 20th	Night	46% 4 10% 23% 16% 2	1816
	21st to end	Night	41% 6% 12% 25% 14% 2	1710
May	1st to 10th	Night	40% 6% 11% 26% 17% 1	2550
	11th to 20th	Night	26% 8% 11% 34% 18% 2	2516
	21st to end	Night	41% 14% 13% 23% 9%	2680
June	1st to 10th	Night	38% 6% 9% 24% 18% 4	1330
	11th to 20th	Night	39% 7% 14% 20% 16% 4	1330
	21st to end	Night	24% 5% 10% 27% 25% 7%	1330
July	1st to 10th	Night	14% 2 5% 18% 32% 28%	2398
	11th to 20th	Night	10% 2 5% 14% 20% 50%	2492
	21st to end	Night	9% 2 3 21% 35% 30%	2674
August	1st to 10th	Night	15% 3 6% 27% 29% 21%	2521
	11th to 20th	Night	19% 5% 6% 35% 30% 6%	2665
	21st to end	Night	22% 5% 12% 29% 27% 5%	3420
September	1st to 10th	Night	18% 4 6% 29% 29% 13%	1900
	11th to 20th	Night	29% 6% 11% 23% 24% 6%	1990
	21st to end	Night	31% 4 15% 30% 15% 5%	2090
October	1st to 10th	Night	25% 6% 13% 39% 17% 1	3659
	11th to 20th	Night	34% 8% 14% 24% 20% 1	3954
	21st to end	Night	41% 7% 14% 27% 9% 1	4457
November	1st to 10th	Night	56% 8% 16% 15% 5% 1	2528
	11th to 20th	Night	57% 6% 16% 13% 6% 2	2603
	21st to end	Night	61% 6% 14% 13% 6%	2791
December	1st to 10th	Night	60% 7% 11% 16% 4	2850
	11th to 20th	Night	72% 7% 11% 8% 2	3507
	21st to end	Night	69% 7% 11% 8% 5%	5174

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	27% 8% 18% 28% 16% 3	180
	11th to 20th	Day	30% 4 19% 30% 11% 6%	180
	21st to end	Day	35% 4 22% 26% 12% 2	198
February	1st to 10th	Day	27% 11% 30% 25% 6% 2	180
	11th to 20th	Day	25% 13% 28% 24% 8% 2	405
	21st to end	Day	25% 9% 30% 25% 11%	382
March	1st to 10th	Day	26% 17% 27% 18% 10% 3	460
	11th to 20th	Day	24% 10% 23% 24% 17% 2	460
	21st to end	Day	24% 19% 25% 22% 10% 1	506
April	1st to 10th	Day	25% 12% 32% 22% 7% 2	460
	11th to 20th	Day	23% 20% 26% 18% 9% 3	452
	21st to end	Day	18% 17% 28% 25% 10% 3	460
May	1st to 10th	Day	16% 12% 31% 26% 12% 3	463
	11th to 20th	Day	17% 13% 27% 26% 13% 4	488
	21st to end	Day	16% 10% 25% 26% 18% 5%	567
June	1st to 10th	Day	21% 10% 24% 25% 17% 4	680
	11th to 20th	Day	16% 16% 25% 29% 11% 3	680
	21st to end	Day	9% 9% 25% 32% 20% 5%	680
July	1st to 10th	Day	5% 9% 33% 32% 16% 4	544
	11th to 20th	Day	4 14% 34% 30% 14% 4	484
	21st to end	Day	5% 7% 32% 34% 16% 5%	531
August	1st to 10th	Day	7% 8% 26% 35% 17% 6%	487
	11th to 20th	Day	5% 5% 26% 33% 23% 7%	477
	21st to end	Day	9% 12% 24% 31% 18% 7%	539
September	1st to 10th	Day	8% 8% 30% 26% 22% 6%	490
	11th to 20th	Day	11% 11% 25% 31% 17% 5%	490
	21st to end	Day	16% 14% 28% 24% 15% 4	490
October	1st to 10th	Day	14% 12% 27% 28% 15% 4	490
	11th to 20th	Day	21% 9% 21% 28% 15% 6%	382
	21st to end	Day	24% 9% 26% 27% 12% 2	330
November	1st to 10th	Day	31% 5% 19% 30% 14% 1	297
	11th to 20th	Day	32% 7% 21% 19% 18% 2	205
	21st to end	Day	31% 7% 21% 22% 17% 3	180
December	1st to 10th	Day	29% 8% 22% 23% 12% 6%	180
	11th to 20th	Day	30% 11% 21% 24% 12% 2	180
	21st to end	Day	30% 5% 19% 30% 16% 1	198
January	1st to 10th	Night	37% 5% 16% 27% 13% 2	760
	11th to 20th	Night	30% 4 16% 32% 14% 3	760
	21st to end	Night	25% 4 17% 37% 16% 2	836
February	1st to 10th	Night	25% 5% 19% 36% 13% 2	760
	11th to 20th	Night	23% 4 22% 32% 18% 2	744
	21st to end	Night	20% 6% 18% 34% 20% 2	628
March	1st to 10th	Night	19% 7% 20% 34% 19% 2	760
	11th to 20th	Night	21% 5% 18% 34% 22% 1	760
	21st to end	Night	20% 4 20% 39% 16% 2	836
April	1st to 10th	Night	15% 5% 16% 40% 21% 3	760
	11th to 20th	Night	15% 6% 25% 35% 18% 2	688
	21st to end	Night	14% 8% 19% 36% 22% 2	570
May	1st to 10th	Night	13% 6% 16% 35% 27% 3	390
	11th to 20th	Night	10% 7% 16% 29% 32% 6%	374
	21st to end	Night	16% 4 10% 36% 28% 6%	411
June	1st to 10th	Night	14% 4 12% 43% 25% 3	380
	11th to 20th	Night	13% 6% 16% 39% 24% 3	380
	21st to end	Night	8% 3 12% 42% 33% 2	380
July	1st to 10th	Night	4 2 9% 42% 40% 3	370
	11th to 20th	Night	2 3 13% 47% 35% 1	368
	21st to end	Night	2 3 8% 41% 43% 3	416
August	1st to 10th	Night	4 4 10% 33% 42% 7%	378
	11th to 20th	Night	3 3 8% 34% 44% 7%	455
	21st to end	Night	4 4 11% 38% 39% 4	784
September	1st to 10th	Night	6% 3 12% 40% 33% 6%	760
	11th to 20th	Night	8% 4 11% 32% 37% 9%	760
	21st to end	Night	13% 4 13% 37% 27% 6%	760
October	1st to 10th	Night	16% 4 11% 39% 28% 2	760
	11th to 20th	Night	18% 4 13% 36% 27% 2	760
	21st to end	Night	23% 3 19% 36% 16% 3	836
November	1st to 10th	Night	30% 4 13% 39% 13% 1	778
	11th to 20th	Night	30% 5% 18% 31% 15% 2	760
	21st to end	Night	29% 4 15% 31% 18% 2	891
December	1st to 10th	Night	25% 4 15% 35% 17% 3	950
	11th to 20th	Night	32% 5% 15% 36% 11% 1	950
	21st to end	Night	32% 4 17% 35% 11% 1	1018

Page generated at 2024-11-07 03:55:49. Version ac07

Copyright © 2024 Attilla Danko.