Cypress Hills Dark-Sky Preserve - CHICO
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cypress Hills Dark-Sky Preserve - CHICO clear sky chart from 2005-11-06 to 2024-12-24.

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	6% 7% 3 7% 5% 5% 5% 4 6% 8% 42%	105948
	Night	5% 7% 3 8% 6% 6% 6% 5% 7% 8% 41%	102805
Transparency	Day	37% 6% 16% 27% 12% 2	105670
	Night	36% 6% 17% 26% 12% 2	102674
Seeing	Day	11% 11% 30% 29% 15% 3	15711
	Night	9% 12% 33% 32% 13% 2	25059

By Month

Percentage Cloud Cover SW (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	2 10% 5% 10% 6% 6% 6% 6% 8% 10% 31%	2219
	11th to 20th	Day	1 5% 3 13% 7% 7% 8% 7% 8% 9% 32%	2220
	21st to end	Day	1 5% 3 8% 7% 5% 5% 5% 6% 7% 47%	2700
February	1st to 10th	Day	5% 10% 4 11% 8% 7% 7% 6% 7% 8% 28%	1710
	11th to 20th	Day	3 9% 5% 9% 7% 7% 8% 6% 10% 10% 27%	1665
	21st to end	Day	3 10% 5% 11% 7% 7% 6% 6% 7% 9% 30%	1413
March	1st to 10th	Day	2 7% 3 10% 7% 6% 5% 5% 7% 9% 39%	3299
	11th to 20th	Day	5% 7% 2 7% 5% 6% 5% 5% 7% 11% 40%	3490
	21st to end	Day	6% 16% 5% 12% 9% 9% 5% 4 5% 7% 23%	3825
April	1st to 10th	Day	5% 11% 3 9% 7% 7% 6% 5% 8% 8% 32%	2286
	11th to 20th	Day	9% 12% 5% 11% 7% 5% 5% 4 6% 6% 29%	2437
	21st to end	Day	10% 11% 4 9% 6% 6% 4 4 5% 8% 33%	2470
May	1st to 10th	Day	13% 14% 6% 11% 6% 4 4 3 5% 5% 29%	4384
	11th to 20th	Day	8% 7% 3 9% 6% 6% 6% 6% 7% 8% 35%	4414
	21st to end	Day	14% 9% 3 8% 5% 5% 6% 4 6% 8% 31%	5161
June	1st to 10th	Day	13% 7% 3 8% 5% 4 5% 5% 6% 8% 35%	2850
	11th to 20th	Day	15% 9% 3 8% 6% 6% 5% 5% 6% 7% 31%	2850
	21st to end	Day	8% 4 1 6% 5% 5% 6% 5% 7% 8% 46%	2850
July	1st to 10th	Day	4 3 2 6% 5% 6% 5% 5% 7% 9% 48%	4740
	11th to 20th	Day	4 3 1 4 3 3 4 4 6% 8% 58%	4740
	21st to end	Day	3 1 1 3 3 3 3 3 5% 6% 68%	5125
August	1st to 10th	Day	5% 4 1 6% 4 5% 5% 4 7% 8% 51%	4194
	11th to 20th	Day	4 4 1 4 3 4 6% 5% 7% 9% 52%	4028
	21st to end	Day	5% 3 1 4 3 4 4 4 6% 8% 58%	4521
September	1st to 10th	Day	11% 6% 2 5% 4 3 3 3 5% 6% 52%	2310
	11th to 20th	Day	12% 7% 2 6% 3 4 5% 3 5% 8% 45%	2161
	21st to end	Day	9% 6% 2 5% 3 3 4 4 6% 7% 51%	2080
October	1st to 10th	Day	5% 5% 2 7% 5% 4 4 4 6% 9% 49%	3170
	11th to 20th	Day	3 5% 2 6% 4 3 4 4 5% 9% 53%	3150
	21st to end	Day	4 7% 3 6% 5% 4 4 5% 6% 7% 49%	3105
November	1st to 10th	Day	7% 12% 4 10% 8% 5% 5% 4 6% 6% 32%	1568
	11th to 20th	Day	3 7% 3 8% 8% 7% 6% 4 7% 9% 39%	1600
	21st to end	Day	4 9% 4 9% 6% 7% 7% 6% 7% 7% 34%	1595
December	1st to 10th	Day	3 10% 3 10% 9% 8% 6% 6% 7% 7% 30%	1400
	11th to 20th	Day	2 8% 3 8% 7% 6% 8% 5% 8% 11% 33%	1755
	21st to end	Day	2 7% 3 7% 6% 6% 6% 4 6% 8% 46%	2463
January	1st to 10th	Night	2 6% 3 8% 6% 6% 7% 7% 10% 12% 33%	4726
	11th to 20th	Night	1 6% 5% 13% 8% 7% 7% 5% 7% 9% 32%	4740
	21st to end	Night	1 5% 3 7% 7% 8% 7% 6% 8% 10% 39%	4983
February	1st to 10th	Night	4 10% 4 10% 7% 7% 7% 6% 7% 9% 29%	2470
	11th to 20th	Night	2 8% 4 9% 7% 7% 8% 5% 8% 11% 30%	2402
	21st to end	Night	2 9% 3 11% 8% 7% 6% 6% 8% 9% 31%	2041
March	1st to 10th	Night	3 7% 3 10% 7% 7% 8% 6% 8% 9% 32%	3570
	11th to 20th	Night	6% 7% 2 5% 5% 4 5% 5% 7% 9% 45%	3490
	21st to end	Night	7% 16% 5% 13% 10% 9% 6% 4 6% 6% 17%	3828
April	1st to 10th	Night	7% 10% 3 10% 7% 6% 7% 5% 6% 8% 32%	1892
	11th to 20th	Night	8% 8% 4 10% 7% 6% 5% 4 8% 8% 33%	1691
	21st to end	Night	7% 9% 3 10% 6% 5% 4 5% 7% 8% 35%	1710
May	1st to 10th	Night	13% 13% 4 10% 7% 4 4 3 5% 5% 32%	2586
	11th to 20th	Night	6% 6% 3 7% 5% 6% 6% 6% 7% 10% 38%	2487
	21st to end	Night	11% 9% 3 9% 6% 5% 5% 5% 6% 9% 31%	2414
June	1st to 10th	Night	14% 6% 2 8% 5% 4 4 4 6% 8% 39%	1330
	11th to 20th	Night	10% 8% 2 7% 5% 5% 6% 4 6% 7% 41%	1330
	21st to end	Night	6% 4 1 5% 3 3 4 4 9% 8% 52%	1330
July	1st to 10th	Night	3 3 1 5% 4 5% 4 4 6% 9% 56%	2220
	11th to 20th	Night	4 3 1 4 3 3 4 3 6% 7% 61%	2220
	21st to end	Night	2 2 1 2 2 3 3 4 5% 7% 69%	2413
August	1st to 10th	Night	8% 4 1 5% 4 3 3 3 6% 7% 56%	2742
	11th to 20th	Night	4 3 2 6% 4 5% 6% 4 8% 10% 49%	2811
	21st to end	Night	9% 5% 2 5% 3 3 4 2 4 6% 57%	3146
September	1st to 10th	Night	9% 6% 1 5% 3 4 4 3 5% 6% 54%	1869
	11th to 20th	Night	9% 7% 2 7% 4 5% 4 3 5% 7% 47%	2015
	21st to end	Night	6% 6% 2 6% 4 4 4 4 5% 8% 51%	2100
October	1st to 10th	Night	5% 6% 2 5% 4 4 5% 4 6% 8% 51%	3800
	11th to 20th	Night	5% 5% 2 6% 5% 5% 4 4 7% 9% 48%	3778
	21st to end	Night	4 5% 3 7% 5% 5% 5% 4 6% 7% 49%	4419
November	1st to 10th	Night	8% 9% 3 9% 6% 6% 7% 5% 6% 8% 34%	2730
	11th to 20th	Night	3 6% 3 8% 7% 7% 8% 6% 8% 8% 37%	2800
	21st to end	Night	3 9% 3 9% 6% 6% 6% 5% 7% 9% 36%	2800
December	1st to 10th	Night	2 8% 3 9% 7% 9% 6% 5% 8% 10% 33%	3000
	11th to 20th	Night	2 7% 4 9% 6% 7% 6% 6% 8% 10% 35%	3656
	21st to end	Night	3 6% 3 6% 5% 5% 6% 5% 7% 7% 50%	5266

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% 6% 21% 25% 4 1	2219
	11th to 20th	Day	45% 7% 14% 20% 12% 2	2220
	21st to end	Day	34% 5% 27% 29% 6%	2700
February	1st to 10th	Day	48% 7% 18% 17% 9% 1	1710
	11th to 20th	Day	45% 8% 18% 21% 7% 1	1674
	21st to end	Day	49% 6% 17% 18% 10% 1	1413
March	1st to 10th	Day	36% 9% 16% 28% 10%	3299
	11th to 20th	Day	36% 7% 22% 24% 10% 1	3490
	21st to end	Day	54% 10% 18% 13% 5% 1	3825
April	1st to 10th	Day	44% 6% 16% 25% 8%	2286
	11th to 20th	Day	51% 5% 12% 24% 7% 1	2440
	21st to end	Day	47% 5% 16% 25% 6% 1	2470
May	1st to 10th	Day	55% 3 14% 22% 5%	4384
	11th to 20th	Day	41% 6% 14% 30% 9%	4418
	21st to end	Day	48% 5% 15% 24% 8%	5162
June	1st to 10th	Day	45% 5% 17% 22% 10% 1	2850
	11th to 20th	Day	48% 6% 13% 22% 11% 1	2850
	21st to end	Day	33% 7% 19% 28% 13% 1	2850
July	1st to 10th	Day	27% 9% 15% 26% 19% 4	4666
	11th to 20th	Day	22% 5% 13% 33% 20% 7%	4659
	21st to end	Day	15% 4 9% 29% 30% 12%	4963
August	1st to 10th	Day	27% 7% 11% 33% 20% 3	4179
	11th to 20th	Day	26% 6% 15% 38% 14% 1	4067
	21st to end	Day	22% 4 13% 41% 19% 2	4520
September	1st to 10th	Day	32% 3 13% 25% 19% 7%	2310
	11th to 20th	Day	37% 6% 14% 28% 13% 3	2161
	21st to end	Day	31% 4 15% 32% 16% 2	2080
October	1st to 10th	Day	31% 4 15% 33% 14% 3	3170
	11th to 20th	Day	28% 4 20% 32% 14% 2	3150
	21st to end	Day	31% 7% 12% 37% 12%	3105
November	1st to 10th	Day	50% 6% 14% 21% 9% 1	1568
	11th to 20th	Day	37% 7% 22% 24% 9% 1	1600
	21st to end	Day	44% 8% 19% 20% 9% 1	1595
December	1st to 10th	Day	47% 8% 19% 19% 6% 2	1400
	11th to 20th	Day	42% 7% 23% 22% 4 1	1754
	21st to end	Day	35% 5% 15% 25% 13% 7%	2463
January	1st to 10th	Night	37% 7% 25% 23% 6% 1	4726
	11th to 20th	Night	44% 6% 14% 19% 13% 3	4740
	21st to end	Night	35% 5% 24% 28% 7% 1	4983
February	1st to 10th	Night	45% 6% 19% 18% 11% 2	2470
	11th to 20th	Night	42% 6% 20% 20% 11% 1	2403
	21st to end	Night	44% 6% 15% 23% 9% 3	2041
March	1st to 10th	Night	42% 8% 18% 22% 9% 1	3570
	11th to 20th	Night	33% 5% 24% 27% 11%	3490
	21st to end	Night	58% 10% 15% 12% 4 1	3828
April	1st to 10th	Night	46% 5% 16% 23% 9%	1892
	11th to 20th	Night	44% 5% 13% 24% 13% 1	1691
	21st to end	Night	43% 5% 15% 28% 8% 1	1710
May	1st to 10th	Night	50% 3 14% 24% 9%	2586
	11th to 20th	Night	35% 6% 16% 32% 11% 1	2488
	21st to end	Night	46% 4 21% 22% 7%	2414
June	1st to 10th	Night	41% 5% 18% 24% 10% 1	1330
	11th to 20th	Night	40% 5% 14% 25% 15% 2	1330
	21st to end	Night	25% 6% 19% 35% 14% 2	1330
July	1st to 10th	Night	20% 8% 14% 34% 22% 2	2185
	11th to 20th	Night	20% 5% 11% 33% 23% 8%	2178
	21st to end	Night	13% 4 9% 31% 31% 13%	2337
August	1st to 10th	Night	26% 5% 10% 36% 20% 4	2734
	11th to 20th	Night	27% 6% 15% 35% 15% 3	2838
	21st to end	Night	28% 3 11% 35% 19% 3	3146
September	1st to 10th	Night	30% 4 13% 28% 17% 9%	1869
	11th to 20th	Night	36% 4 13% 31% 13% 4	2015
	21st to end	Night	30% 5% 15% 31% 18% 2	2100
October	1st to 10th	Night	29% 5% 14% 36% 15% 1	3800
	11th to 20th	Night	29% 4 16% 30% 17% 2	3778
	21st to end	Night	31% 6% 13% 38% 12%	4419
November	1st to 10th	Night	45% 7% 15% 22% 9% 2	2730
	11th to 20th	Night	37% 7% 24% 20% 12%	2800
	21st to end	Night	40% 8% 24% 18% 9% 1	2800
December	1st to 10th	Night	40% 9% 20% 20% 9% 1	3000
	11th to 20th	Night	39% 7% 29% 20% 5% 1	3657
	21st to end	Night	31% 5% 16% 26% 15% 8%	5266

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	7% 17% 33% 22% 16% 6%	180
	11th to 20th	Day	6% 13% 32% 32% 13% 4	180
	21st to end	Day	3 17% 37% 32% 10% 1	211
February	1st to 10th	Day	11% 17% 36% 26% 8% 1	270
	11th to 20th	Day	7% 14% 37% 26% 13% 3	270
	21st to end	Day	4 10% 39% 32% 13% 3	225
March	1st to 10th	Day	9% 13% 36% 29% 12% 2	433
	11th to 20th	Day	8% 10% 37% 28% 13% 4	460
	21st to end	Day	10% 13% 32% 27% 14% 4	506
April	1st to 10th	Day	9% 16% 33% 31% 10% 1	460
	11th to 20th	Day	12% 14% 35% 27% 11% 1	452
	21st to end	Day	17% 12% 30% 27% 12% 2	460
May	1st to 10th	Day	14% 10% 22% 29% 19% 5%	620
	11th to 20th	Day	13% 9% 23% 31% 19% 5%	675
	21st to end	Day	18% 9% 21% 25% 20% 6%	734
June	1st to 10th	Day	16% 12% 24% 30% 17% 3	680
	11th to 20th	Day	18% 14% 32% 23% 12% 2	680
	21st to end	Day	12% 7% 29% 27% 21% 4	680
July	1st to 10th	Day	4 5% 26% 40% 20% 4	671
	11th to 20th	Day	7% 6% 31% 35% 18% 3	668
	21st to end	Day	6% 6% 25% 36% 22% 6%	739
August	1st to 10th	Day	8% 5% 26% 37% 20% 4	550
	11th to 20th	Day	7% 6% 25% 36% 20% 5%	477
	21st to end	Day	7% 9% 28% 33% 18% 5%	539
September	1st to 10th	Day	12% 9% 31% 32% 14% 2	490
	11th to 20th	Day	13% 11% 29% 29% 14% 3	490
	21st to end	Day	15% 14% 33% 25% 10% 4	480
October	1st to 10th	Day	13% 14% 29% 21% 19% 4	300
	11th to 20th	Day	6% 18% 32% 29% 14% 2	300
	21st to end	Day	13% 17% 36% 24% 8% 1	330
November	1st to 10th	Day	16% 17% 36% 21% 9% 1	300
	11th to 20th	Day	9% 23% 40% 20% 7% 1	300
	21st to end	Day	6% 20% 36% 23% 12% 3	297
December	1st to 10th	Day	9% 19% 40% 21% 10% 3	200
	11th to 20th	Day	7% 22% 38% 26% 6% 2	200
	21st to end	Day	8% 11% 27% 38% 12% 4	204
January	1st to 10th	Night	7% 17% 38% 27% 10% 1	950
	11th to 20th	Night	5% 18% 38% 29% 10% 1	950
	21st to end	Night	5% 19% 39% 27% 10% 2	931
February	1st to 10th	Night	9% 13% 31% 30% 15% 2	760
	11th to 20th	Night	5% 13% 43% 27% 11% 1	744
	21st to end	Night	6% 11% 33% 31% 15% 5%	628
March	1st to 10th	Night	7% 10% 38% 33% 12% 1	760
	11th to 20th	Night	9% 11% 33% 34% 10% 3	760
	21st to end	Night	11% 11% 33% 29% 14% 3	836
April	1st to 10th	Night	10% 12% 33% 31% 12% 2	590
	11th to 20th	Night	12% 8% 35% 32% 12% 1	563
	21st to end	Night	13% 9% 31% 34% 13%	570
May	1st to 10th	Night	13% 9% 22% 34% 20% 2	570
	11th to 20th	Night	10% 6% 25% 36% 19% 3	544
	21st to end	Night	18% 9% 21% 28% 20% 3	411
June	1st to 10th	Night	17% 10% 23% 30% 18% 2	380
	11th to 20th	Night	14% 10% 33% 32% 11%	380
	21st to end	Night	9% 6% 24% 36% 20% 4	380
July	1st to 10th	Night	6% 6% 22% 45% 20% 1	370
	11th to 20th	Night	7% 5% 30% 42% 14% 1	368
	21st to end	Night	5% 5% 20% 44% 25% 2	416
August	1st to 10th	Night	7% 4 24% 42% 22% 2	567
	11th to 20th	Night	9% 3 19% 42% 26% 1	564
	21st to end	Night	11% 6% 22% 39% 21% 1	627
September	1st to 10th	Night	12% 4 27% 39% 15% 3	570
	11th to 20th	Night	13% 7% 25% 36% 18% 1	685
	21st to end	Night	10% 9% 31% 32% 15% 4	760
October	1st to 10th	Night	13% 10% 27% 32% 17% 1	760
	11th to 20th	Night	9% 12% 33% 30% 13% 2	760
	21st to end	Night	8% 18% 36% 28% 9%	867
November	1st to 10th	Night	13% 13% 37% 29% 7%	975
	11th to 20th	Night	8% 19% 40% 25% 7% 1	1000
	21st to end	Night	7% 14% 42% 30% 7%	1000
December	1st to 10th	Night	6% 16% 37% 28% 11% 2	1000
	11th to 20th	Night	5% 17% 38% 29% 10% 2	1000
	21st to end	Night	9% 14% 36% 29% 10% 2	1063

Page generated at 2024-12-21 02:13:48. Version ac07

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