Medicine Hat
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Medicine Hat clear sky chart from 2005-11-06 to 2024-03-18.

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	9% 7% 3 6% 6% 3 5% 5% 6% 8% 42%	78112
	Night	7% 8% 3 7% 6% 4 5% 5% 6% 8% 40%	81694
Transparency	Day	40% 7% 16% 25% 12% 2	77792
	Night	40% 7% 16% 23% 11% 2	81536
Seeing	Day	12% 8% 27% 31% 18% 4	14575
	Night	12% 8% 31% 35% 13% 1	24065

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	5% 12% 6% 10% 6% 4 6% 5% 6% 9% 31%	2219
	11th to 20th	Day	5% 7% 5% 12% 7% 4 9% 8% 6% 7% 30%	2220
	21st to end	Day	4 10% 4 7% 7% 3 5% 4 5% 6% 45%	2666
February	1st to 10th	Day	9% 13% 6% 10% 8% 6% 5% 5% 5% 6% 28%	1695
	11th to 20th	Day	8% 12% 6% 9% 8% 5% 6% 7% 7% 8% 25%	1665
	21st to end	Day	5% 11% 6% 8% 9% 4 8% 5% 6% 7% 31%	1413
March	1st to 10th	Day	5% 11% 5% 10% 8% 4 7% 6% 6% 6% 32%	1982
	11th to 20th	Day	7% 9% 4 7% 7% 4 5% 6% 6% 9% 37%	2058
	21st to end	Day	8% 12% 5% 8% 6% 3 6% 5% 7% 8% 33%	2178
April	1st to 10th	Day	8% 9% 3 6% 7% 4 7% 6% 7% 8% 34%	2179
	11th to 20th	Day	11% 11% 5% 8% 7% 4 5% 5% 5% 7% 33%	2307
	21st to end	Day	11% 8% 4 8% 8% 3 5% 4 5% 7% 36%	2340
May	1st to 10th	Day	13% 9% 3 7% 6% 4 5% 5% 6% 8% 35%	2484
	11th to 20th	Day	10% 5% 2 6% 6% 3 5% 5% 7% 9% 42%	2534
	21st to end	Day	21% 6% 3 6% 5% 3 5% 4 5% 7% 36%	2917
June	1st to 10th	Day	13% 6% 2 6% 5% 3 5% 6% 6% 9% 39%	2700
	11th to 20th	Day	17% 6% 3 5% 6% 3 6% 7% 7% 9% 32%	2700
	21st to end	Day	8% 3 2 4 4 3 5% 6% 6% 9% 50%	2700
July	1st to 10th	Day	5% 3 2 4 4 3 4 5% 6% 10% 53%	2700
	11th to 20th	Day	6% 3 2 4 3 3 4 5% 7% 8% 55%	2700
	21st to end	Day	4 2 1 2 3 2 3 4 6% 8% 64%	2938
August	1st to 10th	Day	6% 4 1 3 3 2 4 4 5% 8% 58%	2419
	11th to 20th	Day	7% 4 1 4 5% 3 5% 5% 6% 9% 53%	2299
	21st to end	Day	7% 3 1 3 4 2 4 4 4 8% 59%	2574
September	1st to 10th	Day	11% 5% 2 4 4 2 4 3 4 6% 55%	2209
	11th to 20th	Day	13% 5% 2 3 4 2 4 4 5% 8% 50%	2031
	21st to end	Day	8% 6% 2 4 4 2 4 4 5% 8% 52%	1980
October	1st to 10th	Day	12% 7% 3 5% 5% 3 4 5% 6% 7% 43%	1801
	11th to 20th	Day	7% 7% 3 7% 6% 5% 6% 5% 7% 7% 42%	1800
	21st to end	Day	11% 9% 3 6% 5% 3 5% 5% 4 7% 41%	1770
November	1st to 10th	Day	14% 12% 4 8% 7% 4 5% 5% 5% 6% 31%	1488
	11th to 20th	Day	6% 9% 5% 8% 6% 4 6% 5% 5% 8% 38%	1520
	21st to end	Day	7% 11% 4 9% 6% 4 5% 5% 6% 9% 35%	1469
December	1st to 10th	Day	7% 14% 6% 9% 6% 4 6% 5% 6% 6% 31%	1330
	11th to 20th	Day	6% 11% 4 10% 9% 4 6% 7% 5% 6% 34%	1685
	21st to end	Day	3 9% 3 6% 6% 3 4 4 5% 7% 48%	2442
January	1st to 10th	Night	4 9% 5% 8% 8% 4 5% 6% 6% 10% 34%	4726
	11th to 20th	Night	5% 8% 5% 9% 8% 4 7% 7% 7% 8% 31%	4740
	21st to end	Night	5% 9% 4 9% 6% 3 5% 5% 6% 8% 40%	5022
February	1st to 10th	Night	9% 12% 4 8% 9% 5% 5% 6% 5% 7% 31%	2484
	11th to 20th	Night	7% 11% 5% 9% 8% 4 6% 6% 7% 8% 29%	2402
	21st to end	Night	5% 10% 5% 9% 8% 5% 6% 5% 6% 8% 34%	2041
March	1st to 10th	Night	5% 9% 5% 10% 8% 4 6% 6% 7% 8% 33%	2193
	11th to 20th	Night	7% 10% 5% 6% 5% 4 5% 6% 6% 10% 36%	2068
	21st to end	Night	7% 11% 4 8% 7% 4 6% 6% 8% 9% 30%	2178
April	1st to 10th	Night	8% 11% 4 8% 7% 4 5% 5% 6% 8% 33%	1778
	11th to 20th	Night	12% 9% 4 7% 6% 3 5% 5% 6% 9% 34%	1601
	21st to end	Night	11% 7% 3 9% 6% 4 4 5% 5% 10% 37%	1620
May	1st to 10th	Night	13% 7% 2 5% 6% 3 4 5% 5% 8% 41%	1476
	11th to 20th	Night	9% 5% 2 5% 5% 3 4 5% 6% 6% 49%	1358
	21st to end	Night	18% 6% 2 6% 6% 4 4 4 5% 9% 36%	1358
June	1st to 10th	Night	15% 6% 2 6% 5% 3 5% 6% 5% 8% 41%	1260
	11th to 20th	Night	14% 4 2 5% 5% 3 7% 5% 7% 8% 40%	1260
	21st to end	Night	6% 3 2 4 4 2 4 6% 5% 9% 54%	1260
July	1st to 10th	Night	6% 2 1 3 4 2 5% 5% 6% 9% 57%	1260
	11th to 20th	Night	6% 4 1 4 5% 2 4 5% 7% 9% 53%	1260
	21st to end	Night	3 2 1 2 3 2 3 4 5% 8% 67%	1379
August	1st to 10th	Night	6% 3 1 4 4 3 4 5% 6% 9% 54%	1517
	11th to 20th	Night	5% 3 1 3 3 3 4 5% 7% 11% 53%	1602
	21st to end	Night	8% 4 1 3 4 2 3 4 6% 8% 55%	1782
September	1st to 10th	Night	9% 4 1 4 4 3 4 4 6% 7% 53%	1750
	11th to 20th	Night	12% 6% 2 4 3 2 4 5% 4 8% 49%	1926
	21st to end	Night	8% 4 2 4 4 3 4 4 7% 8% 52%	1980
October	1st to 10th	Night	12% 6% 2 5% 5% 2 4 5% 6% 8% 44%	2158
	11th to 20th	Night	9% 8% 3 6% 5% 3 4 4 6% 8% 44%	2160
	21st to end	Night	10% 8% 3 7% 6% 4 5% 5% 5% 8% 38%	2568
November	1st to 10th	Night	11% 12% 4 7% 7% 3 5% 4 5% 7% 36%	2590
	11th to 20th	Night	6% 10% 3 7% 7% 4 5% 4 6% 8% 40%	2660
	21st to end	Night	5% 11% 6% 7% 6% 4 5% 4 5% 8% 39%	2707
December	1st to 10th	Night	7% 12% 5% 9% 7% 4 6% 5% 5% 6% 33%	2850
	11th to 20th	Night	5% 8% 5% 9% 7% 4 5% 6% 6% 9% 36%	3506
	21st to end	Night	5% 8% 3 6% 4 3 5% 5% 7% 7% 48%	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	48% 8% 19% 20% 5%	2219
	11th to 20th	Day	52% 6% 13% 16% 12% 1	2220
	21st to end	Day	39% 8% 26% 24% 4	2666
February	1st to 10th	Day	56% 7% 14% 17% 7%	1695
	11th to 20th	Day	53% 8% 14% 18% 7%	1674
	21st to end	Day	52% 6% 13% 19% 9% 1	1413
March	1st to 10th	Day	50% 8% 16% 19% 6%	1982
	11th to 20th	Day	43% 7% 19% 24% 6% 1	2058
	21st to end	Day	48% 9% 18% 17% 8%	2178
April	1st to 10th	Day	45% 7% 15% 25% 9%	2179
	11th to 20th	Day	51% 5% 11% 24% 8% 1	2310
	21st to end	Day	47% 6% 14% 25% 8% 1	2340
May	1st to 10th	Day	46% 6% 16% 22% 10% 1	2484
	11th to 20th	Day	37% 7% 15% 28% 12% 1	2538
	21st to end	Day	48% 6% 13% 22% 10% 1	2918
June	1st to 10th	Day	40% 7% 18% 23% 11% 2	2700
	11th to 20th	Day	45% 8% 15% 20% 11% 1	2700
	21st to end	Day	29% 6% 18% 31% 12% 3	2700
July	1st to 10th	Day	24% 7% 19% 31% 16% 3	2626
	11th to 20th	Day	26% 7% 15% 30% 19% 3	2619
	21st to end	Day	18% 5% 14% 33% 24% 6%	2775
August	1st to 10th	Day	24% 6% 16% 31% 18% 5%	2401
	11th to 20th	Day	27% 7% 15% 34% 15% 3	2299
	21st to end	Day	24% 5% 14% 29% 24% 4	2574
September	1st to 10th	Day	32% 4 13% 26% 18% 7%	2209
	11th to 20th	Day	33% 6% 13% 30% 14% 3	2031
	21st to end	Day	31% 6% 14% 31% 16% 3	1980
October	1st to 10th	Day	39% 7% 16% 26% 11% 1	1801
	11th to 20th	Day	40% 5% 17% 25% 12% 1	1800
	21st to end	Day	43% 6% 15% 25% 11%	1770
November	1st to 10th	Day	54% 7% 14% 17% 7% 1	1488
	11th to 20th	Day	44% 7% 19% 23% 7%	1520
	21st to end	Day	46% 6% 20% 21% 7% 1	1469
December	1st to 10th	Day	51% 8% 16% 17% 7% 1	1330
	11th to 20th	Day	47% 9% 19% 20% 4 1	1684
	21st to end	Day	35% 5% 15% 26% 16% 3	2442
January	1st to 10th	Night	43% 9% 22% 21% 4 1	4726
	11th to 20th	Night	49% 7% 15% 16% 12% 1	4740
	21st to end	Night	41% 7% 21% 25% 5% 1	5022
February	1st to 10th	Night	51% 7% 14% 18% 10% 1	2484
	11th to 20th	Night	50% 7% 16% 17% 9% 1	2403
	21st to end	Night	48% 5% 14% 23% 9% 1	2041
March	1st to 10th	Night	46% 10% 15% 22% 7%	2193
	11th to 20th	Night	42% 7% 19% 22% 9% 1	2068
	21st to end	Night	46% 9% 17% 20% 6% 1	2178
April	1st to 10th	Night	49% 5% 14% 23% 10% 1	1778
	11th to 20th	Night	47% 6% 12% 21% 13% 2	1601
	21st to end	Night	45% 5% 14% 25% 9% 2	1620
May	1st to 10th	Night	41% 5% 12% 26% 15% 1	1476
	11th to 20th	Night	34% 6% 11% 28% 20% 1	1359
	21st to end	Night	46% 5% 13% 23% 11% 1	1358
June	1st to 10th	Night	41% 7% 16% 24% 10% 2	1260
	11th to 20th	Night	38% 10% 12% 25% 14% 2	1260
	21st to end	Night	26% 6% 16% 33% 16% 3	1260
July	1st to 10th	Night	22% 6% 16% 34% 19% 3	1225
	11th to 20th	Night	26% 8% 14% 25% 21% 6%	1218
	21st to end	Night	15% 5% 13% 32% 27% 8%	1302
August	1st to 10th	Night	25% 7% 14% 30% 18% 5%	1510
	11th to 20th	Night	24% 7% 17% 27% 20% 6%	1602
	21st to end	Night	26% 4 12% 23% 28% 6%	1782
September	1st to 10th	Night	29% 7% 11% 25% 19% 8%	1750
	11th to 20th	Night	33% 6% 13% 27% 16% 6%	1926
	21st to end	Night	29% 5% 14% 31% 17% 3	1980
October	1st to 10th	Night	37% 6% 15% 25% 15% 2	2158
	11th to 20th	Night	37% 6% 15% 28% 13% 1	2160
	21st to end	Night	43% 7% 16% 24% 9% 1	2568
November	1st to 10th	Night	48% 7% 15% 21% 8% 1	2590
	11th to 20th	Night	43% 6% 20% 20% 10%	2660
	21st to end	Night	43% 6% 24% 18% 8% 1	2707
December	1st to 10th	Night	50% 8% 17% 17% 7% 1	2850
	11th to 20th	Night	43% 8% 25% 19% 4 1	3507
	21st to end	Night	34% 5% 15% 25% 15% 5%	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	9% 6% 32% 31% 17% 6%	180
	11th to 20th	Day	11% 5% 37% 31% 16% 2	180
	21st to end	Day	12% 10% 32% 33% 12% 2	198
February	1st to 10th	Day	18% 12% 35% 25% 7% 2	263
	11th to 20th	Day	13% 6% 31% 31% 15% 3	270
	21st to end	Day	6% 8% 32% 36% 15% 3	225
March	1st to 10th	Day	11% 14% 32% 27% 13% 3	446
	11th to 20th	Day	9% 10% 34% 28% 14% 6%	449
	21st to end	Day	13% 11% 30% 28% 16% 2	462
April	1st to 10th	Day	10% 16% 32% 31% 9% 2	420
	11th to 20th	Day	12% 15% 31% 29% 12% 1	412
	21st to end	Day	16% 10% 26% 32% 14% 3	420
May	1st to 10th	Day	14% 7% 24% 28% 20% 7%	567
	11th to 20th	Day	14% 7% 23% 30% 21% 5%	625
	21st to end	Day	19% 6% 19% 25% 22% 9%	679
June	1st to 10th	Day	14% 11% 23% 30% 18% 4	630
	11th to 20th	Day	17% 12% 28% 27% 14% 2	630
	21st to end	Day	9% 6% 24% 33% 21% 8%	630
July	1st to 10th	Day	6% 4 23% 36% 26% 6%	621
	11th to 20th	Day	8% 5% 24% 38% 21% 4	618
	21st to end	Day	5% 5% 21% 33% 29% 7%	684
August	1st to 10th	Day	6% 4 18% 41% 22% 8%	502
	11th to 20th	Day	7% 3 18% 36% 28% 8%	437
	21st to end	Day	7% 8% 21% 31% 27% 6%	495
September	1st to 10th	Day	12% 9% 26% 28% 22% 3	450
	11th to 20th	Day	13% 6% 24% 31% 22% 4	450
	21st to end	Day	13% 10% 29% 32% 12% 5%	450
October	1st to 10th	Day	18% 5% 25% 28% 19% 5%	271
	11th to 20th	Day	10% 11% 29% 31% 15% 3	270
	21st to end	Day	18% 11% 33% 24% 12% 2	297
November	1st to 10th	Day	27% 9% 29% 23% 12%	270
	11th to 20th	Day	12% 13% 37% 30% 6% 1	270
	21st to end	Day	10% 10% 39% 25% 10% 6%	246
December	1st to 10th	Day	9% 11% 41% 27% 11% 1	180
	11th to 20th	Day	9% 13% 42% 27% 8% 1	180
	21st to end	Day	14% 8% 29% 31% 14% 4	198
January	1st to 10th	Night	12% 12% 35% 30% 10% 1	950
	11th to 20th	Night	12% 10% 35% 32% 10% 1	950
	21st to end	Night	11% 10% 35% 31% 11% 1	931
February	1st to 10th	Night	14% 9% 29% 32% 13% 3	760
	11th to 20th	Night	11% 10% 31% 37% 10% 1	744
	21st to end	Night	8% 6% 31% 36% 16% 3	628
March	1st to 10th	Night	8% 7% 35% 37% 11% 2	760
	11th to 20th	Night	11% 11% 33% 32% 12% 1	752
	21st to end	Night	11% 11% 29% 33% 14% 1	792
April	1st to 10th	Night	13% 9% 34% 31% 12% 1	572
	11th to 20th	Night	16% 5% 33% 34% 12%	533
	21st to end	Night	15% 10% 23% 41% 11%	540
May	1st to 10th	Night	14% 7% 22% 36% 19% 2	540
	11th to 20th	Night	12% 5% 25% 37% 20% 1	473
	21st to end	Night	20% 6% 23% 31% 18% 2	389
June	1st to 10th	Night	17% 8% 25% 35% 14% 2	360
	11th to 20th	Night	15% 8% 29% 37% 11% 1	360
	21st to end	Night	7% 6% 26% 42% 18% 2	360
July	1st to 10th	Night	7% 3 21% 48% 21%	350
	11th to 20th	Night	7% 4 27% 45% 17%	348
	21st to end	Night	4 3 23% 45% 23% 2	394
August	1st to 10th	Night	8% 3 22% 42% 25% 1	501
	11th to 20th	Night	7% 2 21% 43% 27% 1	534
	21st to end	Night	9% 4 23% 38% 25% 1	594
September	1st to 10th	Night	11% 4 26% 43% 14% 1	540
	11th to 20th	Night	15% 5% 22% 41% 17%	666
	21st to end	Night	11% 5% 30% 39% 14% 2	720
October	1st to 10th	Night	15% 8% 26% 34% 17% 1	720
	11th to 20th	Night	14% 8% 31% 33% 13% 2	720
	21st to end	Night	13% 10% 36% 31% 8%	814
November	1st to 10th	Night	17% 11% 35% 29% 8% 1	925
	11th to 20th	Night	13% 13% 39% 28% 6% 1	950
	21st to end	Night	11% 10% 39% 32% 8% 1	950
December	1st to 10th	Night	12% 7% 35% 32% 11% 2	950
	11th to 20th	Night	10% 10% 39% 29% 11% 1	950
	21st to end	Night	13% 9% 35% 33% 8% 2	1045

Page generated at 2024-03-15 12:01:45. Version ac07

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