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 2024-07-16.

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	7% 8% 3 8% 6% 5% 5% 4 6% 8% 39%	89646
	Night	5% 7% 3 8% 6% 6% 6% 5% 7% 9% 39%	89978
Transparency	Day	40% 6% 16% 25% 11% 2	89328
	Night	38% 6% 18% 24% 11% 2	89819
Seeing	Day	11% 11% 30% 29% 16% 4	15159
	Night	9% 12% 33% 32% 13% 2	24435

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% 4 5% 5% 5% 8% 11% 48%	2850
	11th to 20th	Day	6% 4 1 5% 4 4 4 5% 7% 9% 52%	2779
	21st to end	Day	4 2 1 3 4 4 3 4 7% 7% 61%	2937
August	1st to 10th	Day	6% 4 1 5% 3 4 4 3 6% 7% 56%	2388
	11th to 20th	Day	6% 6% 2 5% 4 4 5% 4 6% 9% 51%	2299
	21st to end	Day	7% 4 2 4 3 4 4 4 7% 8% 54%	2574
September	1st to 10th	Day	11% 6% 2 5% 4 3 3 3 6% 6% 50%	2189
	11th to 20th	Day	12% 7% 2 6% 3 4 4 3 5% 8% 47%	2048
	21st to end	Day	10% 6% 2 5% 3 4 4 4 6% 7% 50%	1971
October	1st to 10th	Day	8% 9% 3 8% 6% 4 4 4 7% 8% 39%	1800
	11th to 20th	Day	5% 8% 4 9% 5% 4 5% 4 6% 7% 43%	1800
	21st to end	Day	5% 10% 5% 9% 6% 5% 4 4 6% 8% 39%	1787
November	1st to 10th	Day	8% 13% 4 10% 7% 5% 5% 4 6% 6% 32%	1488
	11th to 20th	Day	3 7% 3 8% 8% 7% 5% 3 7% 8% 39%	1520
	21st to end	Day	4 8% 4 9% 6% 7% 7% 6% 7% 7% 36%	1516
December	1st to 10th	Day	3 10% 3 10% 9% 8% 6% 6% 6% 7% 31%	1330
	11th to 20th	Day	2 8% 3 8% 7% 7% 8% 5% 8% 10% 33%	1685
	21st to end	Day	2 7% 3 7% 6% 6% 6% 4 7% 8% 46%	2442
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	4 4 1 5% 4 5% 4 4 6% 8% 55%	1330
	11th to 20th	Night	5% 4 1 4 4 3 5% 4 7% 7% 56%	1302
	21st to end	Night	3 3 2 3 2 4 4 4 6% 7% 63%	1379
August	1st to 10th	Night	5% 4 2 6% 4 3 4 3 6% 7% 56%	1548
	11th to 20th	Night	6% 4 2 5% 3 4 5% 4 7% 9% 51%	1602
	21st to end	Night	8% 6% 2 5% 3 4 5% 3 5% 8% 53%	1782
September	1st to 10th	Night	9% 6% 1 5% 3 4 4 3 5% 6% 52%	1770
	11th to 20th	Night	9% 7% 2 7% 4 5% 4 3 5% 7% 48%	1908
	21st to end	Night	6% 6% 3 6% 4 4 4 4 6% 8% 51%	1989
October	1st to 10th	Night	8% 9% 3 7% 4 4 5% 4 6% 8% 43%	2160
	11th to 20th	Night	5% 6% 3 7% 6% 5% 5% 4 8% 9% 42%	2160
	21st to end	Night	5% 8% 4 9% 7% 6% 6% 5% 6% 8% 36%	2548
November	1st to 10th	Night	8% 9% 3 9% 6% 6% 7% 5% 6% 8% 33%	2590
	11th to 20th	Night	3 7% 3 8% 7% 7% 7% 6% 8% 8% 37%	2660
	21st to end	Night	3 9% 3 9% 6% 6% 6% 5% 7% 9% 37%	2660
December	1st to 10th	Night	2 8% 3 9% 7% 9% 6% 5% 8% 9% 33%	2850
	11th to 20th	Night	2 7% 4 8% 6% 6% 6% 6% 8% 10% 36%	3506
	21st to end	Night	3 6% 3 6% 5% 5% 6% 5% 6% 7% 50%	5214

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	26% 6% 17% 30% 17% 3	2776
	11th to 20th	Day	26% 5% 14% 28% 22% 5%	2698
	21st to end	Day	19% 6% 13% 30% 26% 6%	2774
August	1st to 10th	Day	26% 5% 14% 30% 20% 5%	2372
	11th to 20th	Day	28% 6% 16% 32% 16% 2	2299
	21st to end	Day	26% 3 13% 29% 25% 3	2574
September	1st to 10th	Day	33% 3 13% 25% 19% 6%	2189
	11th to 20th	Day	35% 6% 13% 30% 13% 3	2048
	21st to end	Day	31% 4 15% 32% 15% 2	1971
October	1st to 10th	Day	40% 6% 18% 25% 11% 1	1800
	11th to 20th	Day	38% 5% 18% 26% 11% 2	1800
	21st to end	Day	42% 6% 17% 25% 11%	1787
November	1st to 10th	Day	51% 6% 14% 20% 9% 1	1488
	11th to 20th	Day	38% 7% 22% 24% 8% 1	1520
	21st to end	Day	42% 7% 20% 21% 9% 1	1516
December	1st to 10th	Day	47% 8% 19% 18% 6% 2	1330
	11th to 20th	Day	42% 7% 24% 22% 5% 1	1684
	21st to end	Day	35% 5% 15% 25% 13% 7%	2442
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	22% 6% 13% 36% 20% 3	1295
	11th to 20th	Night	25% 5% 13% 26% 24% 7%	1260
	21st to end	Night	17% 5% 12% 31% 28% 7%	1302
August	1st to 10th	Night	26% 5% 13% 32% 17% 6%	1540
	11th to 20th	Night	27% 5% 16% 29% 19% 4	1602
	21st to end	Night	30% 4 9% 25% 28% 5%	1782
September	1st to 10th	Night	31% 4 13% 27% 17% 8%	1770
	11th to 20th	Night	35% 4 12% 31% 13% 4	1908
	21st to end	Night	31% 5% 15% 31% 17% 2	1989
October	1st to 10th	Night	36% 6% 17% 26% 14% 2	2160
	11th to 20th	Night	33% 6% 18% 29% 13% 1	2160
	21st to end	Night	41% 7% 17% 26% 9% 1	2548
November	1st to 10th	Night	46% 7% 16% 21% 9% 2	2590
	11th to 20th	Night	36% 7% 25% 20% 12%	2660
	21st to end	Night	39% 7% 25% 19% 9% 1	2660
December	1st to 10th	Night	41% 8% 20% 20% 9% 1	2850
	11th to 20th	Night	37% 7% 29% 21% 5% 1	3507
	21st to end	Night	31% 5% 16% 26% 15% 8%	5214

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% 19% 2	645
	21st to end	Day	5% 5% 26% 36% 22% 6%	684
August	1st to 10th	Day	8% 5% 24% 38% 21% 4	507
	11th to 20th	Day	8% 6% 22% 38% 20% 6%	437
	21st to end	Day	6% 8% 27% 34% 19% 5%	495
September	1st to 10th	Day	12% 9% 33% 30% 14% 1	450
	11th to 20th	Day	12% 10% 28% 30% 15% 4	450
	21st to end	Day	14% 13% 33% 26% 11% 4	441
October	1st to 10th	Day	14% 11% 30% 20% 21% 5%	270
	11th to 20th	Day	6% 17% 32% 29% 14% 2	270
	21st to end	Day	14% 16% 35% 25% 9% 1	297
November	1st to 10th	Day	17% 15% 36% 21% 10% 1	270
	11th to 20th	Day	8% 21% 41% 22% 8% 1	270
	21st to end	Day	5% 20% 37% 22% 13% 3	268
December	1st to 10th	Day	8% 17% 41% 22% 9% 3	180
	11th to 20th	Day	6% 23% 36% 27% 7% 2	180
	21st to end	Day	9% 11% 26% 38% 13% 4	198
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	8% 6% 30% 42% 13% 1	360
	21st to end	Night	4 5% 21% 44% 25% 2	394
August	1st to 10th	Night	6% 3 24% 42% 22% 2	537
	11th to 20th	Night	9% 3 19% 41% 27% 1	534
	21st to end	Night	11% 5% 22% 40% 22% 1	594
September	1st to 10th	Night	13% 4 28% 38% 14% 3	540
	11th to 20th	Night	12% 7% 24% 37% 18% 2	648
	21st to end	Night	9% 8% 31% 33% 15% 4	720
October	1st to 10th	Night	13% 10% 27% 32% 18% 1	720
	11th to 20th	Night	9% 12% 33% 29% 14% 2	720
	21st to end	Night	8% 18% 35% 29% 9%	821
November	1st to 10th	Night	14% 13% 37% 29% 7%	925
	11th to 20th	Night	8% 17% 41% 25% 7% 1	950
	21st to end	Night	6% 13% 43% 30% 7%	950
December	1st to 10th	Night	6% 14% 37% 29% 12% 2	950
	11th to 20th	Night	5% 16% 38% 29% 10% 2	950
	21st to end	Night	9% 14% 36% 29% 10% 2	1045

Page generated at 2024-07-13 08:19:50. Version ac07

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